My advice is to ride as many bikes a possible. Every combination of frame material aluminum, steal, carbon, combinations. But the best thing you can do that will serve you now and in the future is to get a BIKE FIT. Serrota and Seven (high end Frames) offer a bike fit to help riders make new purchases easier, and more accurate from the start. Starting with a frame that fits your body type first, and then tinkering with the stem, seat post etc... later, give you more comfort, and improved handling.

Once you have your own body specs and frame requirements then go shopping. That the sales person pull out the frame specs for each bike in you price range to see what matches up with you specs. Better yet go online and check them yourself. This search for dealers in your area. LBS's are limited to carrying on a few brands of bikes - sometimes by finances and mostly by regional sales contracts. Shop around, ride a lot of brands. But start with a BIKE FIT