You already got a ton of advice, but don't be afraid to shop around. My local REI didn't have a great selection of bikes but one of the LBSes I went to (Revolution) ended up having the perfect fit. Could also look for non-chain/family owned LBSes as well, they tend to have a much more varied selection and might even have a decent selection of used bikes (for example, College Park Bicycles has quite a collection of used bicycles on display along with new models).
Good luck
