I was in the same boat a couple of months ago. Based on my now vast two months of experience with shopping and owning, here are my suggestions.
- Ride lots of options. Spend as much time on the bikes as you can.
- Spend more time than you think is necessary getting a bike that fits. If you find a friendly, well stocked shop, try riding one a little too big and one a little too small so you can begin to understand the difference.
- If you haven't ridden and are not in good shape with good flexibility, your aches and pains will move with every ride as your technique and conditioning improves. You will be amazed at how much easier it gets - quickly.
- Enjoy the process. You'll find bike shops that want to get you out the door with a bike in 10 minutes and you'll find shops that want to spend whatever time it takes to get you on 'your perfect bike'. Keep looking until you find the latter.
I rode Trek, Masi, Lemond, Giant, Bianchi, Motobecane and Specialized. Sat on and looked at lots of others. Ended up with an '03 Bianchi Eros ($750 on year-end closeout). It is the perfect bike for me, for now.
Enjoy.
Balding Middle Aged Fat Guy