When it comes to choosing accommodation in sochi, it depends on season and activites you would like to do in Sochi. During summer time it is popular to repose at the seaside, sea is hot, there are lot of tourists and things to do. These areas are perfect if you love relaxing on the beach - Adler, Hosta, Kudepsta, Sochi. (Sochi is not only the name of the city, but also central district in it, also Sochi is the nightlife center). If you arrive during winter time, you would probably like to visit ski resorts and go skiing or snowboarding. Four ski resorts named Alpika-Service, Gazprom Laura, Gorky Gorod and Rosa Khutor - all are outstaning places for a winter vacation. So for a winter tourist best places to stay are - Krasnaya Polyana, Esto-Sadok, Gorky Gorod or Rosa Khutor (last two offers only hotel-type accommodation).
At this point, if you are planning a visit to sochi - we recommend you (and it would be wise from your side) to start looking both for a desired type of accommodation and in the right area, because there are about 40 kilometers between 3 main areas - Ski resorts - Adler seaside - Sochi seaside.