I bought a Hero two weeks ago at Radio Shack (they were on sale for $49.99, upgrade or new line). Last week I reserved an Evo at the same RS. I'm like you in that my area won't get 4g for a long time so that isn't a selling point for me. I plan on returning the Hero and getting the Evo because of my eyesight... larger screen = no reading glasses. Yes, my decision to get the Evo is based solely on my poor reading vision and the Evo's large screen.

I am 100% certain that I will appreciate, love even, the other improvements vs the Hero! But I could live happily with the Hero.
Assuming you don't have any special needs (or wants as is my case), I would go with the Hero. The Hero is a good phone, especially for a first time smartphone owner. It is currently $79.99 at RS (upgrade or new line) but that may go back down when the Evo hits. Just 1 year ago, who would have imagined that a phone with the Hero's specs could be bought new for $50-$80? Whatever you decide, you'll be getting a good/great phone and in a year you can upgrade again to the new greatest phone.