OP - tell us a little more about yourself. How much riding do you plan on doing each week? How old are you? Is the $770 a stretch for your current budget? All of this will help us.

This what I've been told - the more you ride, the better components you should look at - simply a durability issue. Also, the higher end components shift a better and are lighter with each step you improve.

There is a wisdom in not spending too much on your first bike. Buy something well within your budget and see if you enjoy it. If you do, in a couple of years, make the jump to newer/nicer/lighter/whatever.

Also, keep in mind the bike is only part of the budget. You will want a decent pair of riding shorts and helmet for sure, and probably pedals and shoes, etc. That all adds up.

EDIT: Just missed your post above. You are already far ahead of any walmart bike. So from there, you are safe. You could do 30-50 miles on the bikes you've described. How many LBS's (local bike shop) do you have nearby? Go check them all out. Every company has a bike that fits what you've described. Go ride them. One may call your name, while another just doesn't float your boat. The one that calls your name is the one to buy....you'll ride it more. By calling your name, it could be a slightly different geometry that is just more comfortable for you, or it may be more lively, or it just may look HOT. Whatever it is, you'll probably know.