Rain and Flooding
Maesai has a pronounced wet season during which it is likely to experience flooding 2 or 3 times. The Ruak River rises quickly and falls almost as quickly. It is not uncommon for there to be some flooding in the centre of town, but not the border crossing itself. On 5th September 2014 there was a heavy overnight storm which caused an exceptionally high river flow and flooding and the river flowed over the border bridge (in the picture). Some of the market areas are especially low lying and suffered worst. Many of the accommodation places described in 'sleep' also suffered though few appeared to suffer damage to their guest rooms - some exceptions are noted below.
By bus from Chiang Rai or Chiang Mai. Buses from Chiang Rai are very frequent (every 15-30 min), cost 40 Baht (one way) and take about 1.5 hours, while Green Bus line has minibuses departing approx when full for 46 baht. (Sep 2014)
Buses from Chiang Mai take about 4 hours (210 baht one way). All public buses terminate at a bus station well south of Mae Sai (Maesai), so you have to continue onward to the city proper with red songthaews waiting at the bus station (15 baht per passenger fixed fare). The blue songthaews to/from the Golden Triangle and Chiang Saen (50 baht, 45-60 minutes), on the other hand, leave from a stand in the city centre a few hundred metres down the street from the border in front of the pharmacy on the corner of Thessaban Road Soi 8. The last blue songthaew that departs for Chiang Saen leaves at 2PM.
There are also day-tours taking visitors from Chiang Rai to Mae Sai, the Golden Triangle, and a couple of other places to see on the way as well. Tourist minibuses are more expensive (around 800 baht for a day tour from Chiang Mai including lunch) and, if fully loaded (but this is not always the case), are much less comfortable. However, this is still an option worth considering, if you want to combine your visa run with a sightseeing tour through Chiang Rai province.
There are several minibus services which run between Chiang Mai and Mae Sai, tickets for which can be purchased at most tourist and travel agencies in Chiang Mai. Prices are approximately 700 THB for the round trip which takes 5 hours each way, with a 1-2 hour stopover mid day as people cross the border for shopping and re-entry stamps.
Mae Sai is quite small and can easily be covered on on foot unless you stay in accommodation well out on the road from the south, or you want to travel to the Tesco supermarket almost at the bus station.
Mae Sai is quite an underestimated town as many visitors just breeze past it on their way to the Myanmar border on a visa run. But if you would like to visit an authentic Thai border town there is much to see here for you.
There are plenty of small shops lining both sides of the street leading to the border crossing that sell:
Kik Kok restaurant is about 1Km up from the border on the right as you walk in that direction and there are a few Thai restaurants about this distance along the main road away from the tourist shops near the border. It closes about 8pm.
The one immediately next door, run by Chinese descent people will give you a good feed quite cheaply even later, with alcohol if you want it, and the menus are easy to work on. They are either in English or with pictures of what you get.
A few hundred metres further on the same side of the main road, opposite Chour Palace Hotel, is Jee Jee restaurant with good and reasonably priced food specialising in fish dishes. They have an English menu, but there's no English sign except the unmissable ones pointing to the toilets.
Those wanting a fix of comfort food can visit the new Hongfah Plaza, a small shopping mall off the main street, about 500m on the right as you walk from the border. There's an ice-cream parlour, Black Canyon Coffee and some bakeries selling cakes and sandwiches.
There are several comfortable coffee shops on the main road leading to the immigration checkpoint. There's little in the way of bars are some nice bars and nightclubs in town (which seems to be suffering from a slackening of business) but the Maesai Complex Hotel (see its entry in 'sleep') runs an outside bar in the evenings.
There are few budget places in the usual booking sites so the following is offered (September 2014). In general, the price/standard is not as good as many other Thai towns. Prices are for rooms with a fan but no aircon quoted in September 2014 which is off season.
To the west of the border crossing along Thetsaban 21 which passes along the edge of the market, is the greatest concentration of budget accommodation. Off season prices are mostly 250 to 350THB.
First is an unnamed (in English) guest house on the left still within the market.
Next on the left and still in the market is S House Hotel, no details except that it is in the budget range.
Also on the left is Bamboo House, just before the first trees and the OK Restaurant . It has been recently been partially renovated. It's basic and has the cheapest rooms, from 200 THB though they are a touch gloomy, but there's nothing cheaper and they have nothing actually wrong with them though short on the nice to have features (wardrobe, outside tables) and little English is spoken by the rather unenthusiastic staff.
On the right after the long closed Monkey Island Bar is the YeeSun Hotel with prices from 400THB, a barnlike lobby with just a couple of chairs and rather unenthusiastic staff.
From here you come to a fork in the road....
In the centre is a coffee shop behind what appears to be a shrine which is an office for the turquoise coloured Mom Home, a modern guest house on the hill to the left. The CCTV in the office suggested this to be a quality place. Prices from 300THB. Phone: 089-9549017, but no English Email: firstname.lastname@example.org
On the right is AQ House. Prices from 300 THB and reasonable quality. 089-4322220.
You will come to a 'Police Checkpoint' but it seems to be simply a small 'cop shop' though in several days when we were there the only observed activity was to receive a corpse floated across the river from Myanmar!
Straight ahead by the river is the Maesai Riverside Resort though don't read too much into the word 'resort'! Family owned, this place has rooms and a bar/restaurant (prices fair and beer at little more than shop prices) overlooking the river. It's a bit run down and the standard of the rooms varies but it has great family staff (Jan, the manager speaks English) and an off season price from 250 THB (300 THB in season) you're unlikely to do much better for a place with river views. Accessible from by the river or from the road above - don't stop at the first cabin but go directly to the bar. Phone: 0892352044 (English spoken)
Finally, there's the Maesai Guest House which is more of a resort with individual A-frame bungalows from 350 THB off season, 500 THB high season. A pleasant owner, a bar and restaurant, and bungalows right on the river provide appeal to many travellers. In September 2014 the low lying bungalows and reception/bar were very badly hit, but as of February 2015 they have been restored and the WiFi is still excellent, but come rainy season you should check ahead to be sure. Phone: 053-732021, 053-732481, a little English spoken.
Taking the earlier left fork... Mom Home is up on the left (see above).
On the right is a small guest house called Kitipong House. 300THB.
Also the best place to sleep on the right is the SaiLomJoy, The Boutique Hostel which describes itself as a boutique hostel and spa, and is advertising at 1,500 THB included breakfast and free high speed WIFI. There is also an access from the right hand fork road, where coffee and beverage are also available. Phone 09-4165-1177, www.sailomjoy.com
At the end and to the right is the previously mentioned Police Checkpoint.
From Tachileik (sometimes written as Tachilek), one can travel as far as Kengtung (Thai Chiang Tung) provided you hire a tour guide, 160km away, but to travel to the rest of Myanmar, a visa in advance is needed. Transit travelers can arrange for a visa and can have their passport sent to their port of exit. Some local NGOs  are worth visiting to see some of their humanitarian work.