Aha. While reading for other info in Bicycling Magazine's NEW CYCLIST HANDBOOK I stumbled across this interesting tidbit:

"But it is known that the energy used in cycling varies dramatically as speed changes, thanks to wind resistance."

How about that?

I keep thinking about the speed/distance thing, and how there aren't any really good places to ride near me that I could really ride 20 or 30 miles or more without simply staying on busy streets.

However, it finally hit me that (duh) the faster I can ride those miles, the more likely I am to drive somewhere else to ride. Total time consumed by riding would have to include travel time, after all. And of course there's the fact that easier riding would mean more fun riding.