From Tokyo Station, Odawara is 35 minutes on the JR Tokaido Shinkansen, or 100 minutes on the ordinary Tokaido Line.
From Shinjuku, it's 120 minutes on the Odakyu Line, which takes its name from the city — Odakyu being short for Odawara Kyukō, or "Odawara Express". If you have a JR Pass and want to use JR trains, from the western end of the Yamanote Line (Ikebukuro, Shinjuku, Shibuya), you can ride the JR Shonan-Shinjuku Line rapid service train, which goes to Odawara. Note that the Shonan-Shinjuku Line local service does not go to Odawara, so if you are using the local service, change to a Tokaido Line train at Yokohama, Totsuka or Ofuna. Otherwise, you will end up on the eastern end of Kanagawa Prefecture, while Odawara is on the western end.
Odawara Castle (小田原城, Odawara-jō), . 09:00 to 17:00 (admission until 16:30), daily except December 29th to January 1st. The most popular sightseeing spot in Odawara. The castle tower commands a view of the whole of Odawara city and ancient objects such as weapons and tools are on display. Basic English descriptions are available. And there are various event around the Odawara castle. For example there are The fifth Houjyou festival and ume-festival. ¥300 adults, ¥100 children.
Odawara station. Five lines pass in Odawara station. We can use the Tokaido Line, Odakyu Line, Hakone Tozan Line, Daiyuuzan Line and Tokaido Shinkansen. Odawara Station was remodeled in 2005.
Chinriu Honten (ちん里う本店).  A shop around Odawara Station with products made of Ume apricot since 1871. In the back of the shop, it features a historical section with a barrel more than 140 years old made to produce umeboshi (pickled ume) and it also displays a series of pickles dated since the foundation of the company. The company itself was founded by Mr. Monya Komine, who was chief cook of Odawara castle and is run by the Komine family in its fifth generation. You can taste a wide selection of products for free and on weekends there often is a foreigner who can help you with additional information.
Ume festival. A festival held around February to contemplate the blossom of ume flowers in the area of Soga. Shuttle buses are available from Odawara station.
Houjyou fifth festival. Large festival held in May. A large number of people massed around the Odawara castle. Many people open a stall on the street. For example, they are a shop selling skewers of barbecued chicken and a shop selling yo-yo and so on. Local people carry a precable shrine. This festival is very lively.
Karaoke lounge. There are many Karaoke lounges in Odawara. In these lounges, you can sing many songs, and also you can drink all you want.
Kamaboko. Kamaboko is a special product of Odawara.Kamaboko made from a white fish flesh. Recently, there are cherry blossom design in kamaboko. There are many famous Kamaboko shops in Odawara.
Himono. Himono is dried fish and Odawara is well known for its himono made of Aji (a type of horse mackerel)
Umeboshi. Farmers around Odawara cultivate plums that are used to make traditional sour pickles called umeboshi.
Odawaradon. Odawaradon is a ricebowl dish that is offered in many restaurants in Odawara using typical local products such as kamaboko and umeboshi.
Daruma:  A traditional tempura restaurant founded during Meiji Area (1868 - 1912) about 10 to 15 minutes walking distance from Odawara station. (だるま料理店小田原市本町2-1-30) The building is listed for the protection of historic monuments.
7th nest, a stylish jazz bar, 神奈川県小田原市栄町1-14-57 ジャルダンビル7F, 250-0011, Japan (200 meters from Odawara station. Take east exit, follow main road about 100 meters to the crossing and on the right you will see Odakyu OX and Yoshinoya. The bar is on the right side of Yoshinoya, opposite Odakyu OX. 7th floor.), ☎ +81 465-23-3311, . Cool jazz bar. Personnel speaks English. Just a 2 minutes from the east exit of Odawara station. Mid-range prices.