This is a place well worth a visit when you are in Chiang Mai; it will not be possible to see/do all the sights and attractions in a single day so cherry pick your favourites. The location is saved to the following map 
Formerly known as Doi Angka, the mountain now bears (since 1899) a shortened version of the name of Chiang Mai's last sovereign, King Inthawichayanon. During his reign, he had, with great foresight, expressed his concern for the forests of the northern hill country as the watershed for all of central Thailand. The modern study of rain forest hydrology has borne out his early convictions and given substance to Thai folklore which describes this hill region as the home of the Phiphannam, the 'spirit who shares water'. Before the King died near the turn of this century, he commanded that his remains be placed at the top of this mountain: his ashes at the summit stupa are visited by thousands of people each year.
It is the highest mountain in Thailand,at 2565 metres (8415 feet), just a little higher than Australia's highest (Mt Kosciuszko) which is 7310 feet or 2228 metres,and although it is relatively cold up top, it never snows there.
The various sub montane forest formations at higher elevations are a unique asset of the park. They have dominant species belonging to temperate climate families rather than tropical. The summit area supports the only red rhododendron in Thailand (R. delavayi); it blooms from December through February. There are also two white-blossomed species abundant on Doi Inthanon which are restricted to only a few other sites.
Where mists are persistent, the slopes carry a moist hill evergreen or 'cloud forest' with many epiphytes, plants which live on tree trunks and branches but do not receive their moisture and nutrients from the host tree as do true parasitic plants. Instead, they are nurtured by the accumulation of dust particles and humus around their 'root' area and the moisture retained there, augmented by frequent bathing in cloud and mist. Epiphytic orchids are also abundant, along with lichens, lianas and fern.
At mid-elevations, 800 - 1500 meters, two species of pine are present, Pinus merkusii mixed with dipterocarp in the lower range, and P. kesiya with oak and laurel on drier slopes in the upper range. The pines are thought to be a relic from a prehistoric cooler climatic period when flora from the Sino-Himalayan region migrated southward. At the mid-elevations of the park, much of the forest has been removed by the activities of swidden cultivators and the slopes have converted to fire climax grasslands.
Mid-day temperatures hover about 10 to 12 degrees Celsius during the day (there is a thermometer at the top). Keep in mind that in the wet season, there is near-perpetual cloud there, so you can see little.
One route of Chiang Mai Travel by road Chiang Mai- Hod (Highway 108) through Hang Dong and San Pa Tong district to Chom Thong. Prior to Chom Thong, approximately 2 miles, turn right along the road Chom Thong- Inthanon (Provincial Highway No. 1009) will start the Doi Inthanon at mile 8 (Mae Klang waterfall) and cut to the summit of Doi Inthanon a total length of 49.8 km
Second path of travel along the route Chiang Mai - Hod (Highway 108) past Amphoe Hang Dong, San Pa Tong, Chom Thong and Hod. Of the route travel by Hod - Mae Sa Raing (Highway 108) through Ob Luang National Park. And turn right to Amphoe Mae Chaem by Line Ob Luang - Mae Chaem (Provincial Highway No. 1088) on route to Mae Chaem - Doi Inthanon. (Provincial Highway No. 1192) to the summit of Doi Inthanon. Street Chom Thong - Doi Inthanon. (Provincial Highway No. 1009 at Km 38-39).
Route 3, which is the route to Doi Inthanon is rather difficult. By the way from Chiang Mai by road Chiang Mai - Hod (Highway 108) past Amphoe Hang Dong And San Pa Tong district. Turn right along the road from San Pa Tong district - Ban Kat (Provincial Highway No. 1013), followed by the path Provincial Highway No. 1284 or the through Khun Wang. And the road to Chom Thong - Doi Inthanon (Provincial Highway No. 1009) at kilometer 31 near the National Park.
To get there, you can either drive yourself, hire a car through your hotel or a travel agent, join an organised minibus tour, or be a little adventurous and hire a songthaew for the day.
A songthaew (two bench open-air taxi) will cost you about 2,000 baht for the day, including petrol (ask first!)
A minibus tour will cost around 1,100-1,200 baht with an English-speaking guide. The trip includes visits to the peak, two waterfalls, twin chedis, a royal development project, and a Karen village (somewhat uninspiring). The price also includes all entry fees. It is far cheaper to book direct with the tour operator rather than through a hotel or agent. The tour is from approx 08:30 to 16:30. All fees and (indifferent) lunch are included and you will be picked up and dropped off at your hotel (costs as at June 2011 using Journey Tours of Chiang Mai). The Journey Tours operation is professional and has very safe drivers. It is likely the other operators have similar standards.
It takes two to three hours to get there, and you will pay the entry fee for each person (not the driver, if it is a hire),and also the car entry fee. Make sure you book your planned itinerary with all potential stops before you hire the driver or he will charge you extra.
As you drive up the winding road to the top it will become steadily cooler. At the top you can walk around and check out the sights there. There is a shop for souvenirs and also for drinks and snacks. (also toilets).
Borichinda Cave, Km. 8.5 (located next to Mae Klang Waterfall). The limestone cave has beautiful stalactites and stalagmites and a small stream inside. When glittering in the sunlight, the cave is extremely gorgeous. Entails a 10-minute drive and a walk of some 2 hours from the Mae Klang Waterfall.edit
The King and Queen Twin Chedis, (Approximately 6 kms from the summit.), . The brown Pra Mahathart Napamaythaneedol Chedi (พระมหาธาตุ นภเมทนี"ล) was erected in 1987 in honour of the King and the more feminine, lilac coloured, Pra Mahathart Napapoommisiri Chedi (พระมหาธาตุนภพลภูมิสิริ) for the Queen in 1992. Inside the chedis Thai people and visitors alike leave offerings of flowers and incense sticks as a mark of respect to the well-loved monarchs. The view is tremendous, and the gardens are beautiful. Escalators are available to those who do not want to walk up the many steps.40 baht/person. edit
Mae Klang Waterfall (น้ำตกแม่กลาง), Km. 8. A large waterfall and the easiest to get to. The waterfall is the first gate to Doi Inthanon National Park. It is beautiful and has water all year round; therefore many Thais come to swim, picnic and relax here on a sunny day. At the side of the falls, there is a trekking trail to the Tourist Service Centre (km 9), where you can admire the exhibitions of nature and wildlife in Doi Inthanon. edit
Mae Ya Waterfall (น้ำตกแม่ยะ), (Although it's situated in the park to explore it, you have to go to another different entrance.), . One of the biggest waterfalls. Keep you entrance ticket, as you can access all the entrances with the same ticket on the same day. If not, you may have to purchase a new ticket.edit
Siriphum Waterfall (ลานกางเต้นท์ น้ำตกสิริภูมิ), (23 kilometers along the 1009 from Chiang Mai, turn left down a dirt path and it's about 100 meters to place). The Waterfall was formerly called “Lao Lee Waterfall”, which was named after the headman of a nearby tribesman village. It was later named “Siriphum” to enhance the prestige of His Majesty the King and Her Majesty the Queen. What makes this waterfall stand out is its height, it towers high above the surrounding trees. edit
Sirithan Waterfall (น้ำตกสิริธาร), (Towards the bottom of the mountain along 1009.). Flows down from a cliff with a height of about 50 meters from the base of the waterfall, cascades down into two layers together very nicely. Flows into the Mae Ping River. High water content and flow throughout the year.edit
Wachirathan Falls (น้ำตกวชิรธาร), (About 1 mile further down the 1009 from Sirithan on the left). (lit. Diamond Creek) a beautiful waterfall that flows down a granite escarpment. Although segmented, its falls have a cumulative height of 80m.edit
Ang Ka Nature Trail (อ่างกา), Km. 48 (Located across the other side of the road from the Cafe), . A combination of the highland peat swamp and hill evergreen forest situated at the mountaintop, features a special eco-system found nowhere else. Follow a 400-m-long wooden bridge; you will be introduced to a unique atmosphere of the Himalaya.edit
Kew Mae Pan Nature Trail, Km. 42. Closed from 1 June to 30 October each year. You should not miss the jungle trekking - it's compulsory to hire a guide however the scenery at the trail is well worth it.200 baht per group at the entrance, where as if you hire guide for the trek at Chiang Mai, it's about 600 baht per person. edit
Hmong Market, Km. 31. Driving up to Doi Inthanon, you shouldn’t miss shopping for handmade products (you can watch and buy their weavings), temperate vegetables, flowers and freshly picked fruits from tribal sellers dressed in colourful embroidered costumet.edit
Ganesh Himal Museum, Ganesha Museum, Km. 35, Chiang Mai Hod Road, Tambol Yangkram, Doi Lor District, Chiang Mai Province, ☎ 0-5326-9101, 08-9855-8552, 08-9430-4050, . 9:00 am to 5:00 pm. On the way back to Chiang Mai, you may also want to visit the Ganesh Temple/Museum (well worth a look even if you are not Hindu or Buddhist).Free Entry. edit
Bo Sang Umbrella Village, East of Chiang Mai (From Chiang Mai City, take Chiang Mai - Sankampaeng Rd., and turn left on to Bo Sang - Doi Saket Rd. The entrance to the village is only a few meters from the intersection), . 08:00-17:00. A stop at the Bo Sang Umbrella Village (very touristy), gives you a chance to see a lot of beautiful painted Umbrellas and also Fans. There is a huge array!Decent sized hand-crafted/hand-painted parasols sold for about 60 baht. edit
Why not continue your exploration of the North of Thailand even further by traveling the Mae Hong Son Loop.