If your looking to do longer distances (you say 30-40 miles) I would look at something with gears. I have a tricross s-works I use on the road with road tires, and it has been great. The cyclocross bikes are great because they allow you to run different size tires, where the other bikes you mentioned do not have the clearence for larger tires.
For a first road bike purchase, I'd suggest going to your local bike shop to look around at what they have to offer, and they can make sure you get the bike that suits your needs and they can fit you to the bike.
If you know your size and your comfortable with ebay, then that is a good option too.