Hi Mike,
I'm not an expert but I can give you a few tips that I've learned over the years. First, I would recommend going to a bike shop when they're not busy and get fit for a frame. Most places will do this for you for free. Even if they charge you a small fee it's worth it.

Also, don't buy any bike that has the button shifters on the inside of the hoods. Get something with the shifter levers behind the brake levers. The button shifters are troublesome once you start spending time with your hands of the drops. You just can't reach those buttons with your thumbs.

Then you need to figure out if you want a double or triple chain ring on the crank. A lot of hard core riders want the double - the small chainring is typically called the granny gear - but the triple really can help you get up those hills. I have a triple and as I ride more I use it less and less, but when I need it I'm glad it's there. I once rode around Lake Winnipesaukee in New Hampshire. I don't think I was on flat ground for more than a mile at any one time. That was a day I was glad I had the granny gear.

I have a Cannondale R400 that I bought several years ago. It was at the time Cannondale's entry level road bike. The rear cassette is only an 8-speed. But I upgraded the shifters to the levers I mentioned earlier and put a better handlebar on it, one with a slight rise on the drops for my palms. I also have Time ATAC mtn bike pedals on it, mostly because of a bad knee (these pedals allow your foot to pivot in the pedal a little more than some others). Also, I like the mountain bike shoe because the cleat is recessed in the sole so you can walk around without banging your cleats on the ground.

This set up suits me fine for the kind of riding I do. The nice thing about all of these bikes is you can always upgrade components once you have a good frame. I think Cannondale makes some of the best. And they are made here, or used to be anyway, if you care about that kind of thing. Get out there and have fun. 40 MPH is a hoot on a 23 cm tire.
Bstrgrds,
Doug