I have this:
http://www2.giant-bicycles.com/en-US...yle/600/28409/ and it's good on the street and trails. Buying a bike is sort of like buying a car. Test drive a bunch and get the one that's most comfortable for you in the price range you want. As mentioned above pick a shop with a good reputation for repairs and that is close, it's much easier then when you need maintenance later on. Good luck!