A good place to start is at your LBS. if you aren't stuck on a certain brand, you might as well look around. Giant has an excellent reputation for very good value (bang for the buck). Specialized makes great bikes also, as does Trek. Fit is going to be super important for you, so keep your BS meter tuned when talking to shop peeps. Try as many as you can. If the size isn't right, don't let them try to make the wrong frame work work for you.