Ride Update - FINALLY! I got to take the bike out and try the new cassette. A couple observations:

The first has nothing to do with the size of the cassette (is size the correct term?), but more with just getting a new chain and cassette. They were definitely worn, as the difference is night and day. It may be that I just don't remember when the bike was new, but I don't think my gears ever changed this smoothly or quickly...I mean it was instant!

Now as far as changing to the 12-23, I can't thank you guys enough for that advice. Even if my cassette wasn't worn, it would still have been worth the money to me to make this switch. You guys are right, in flat Jacksonville, this sizing makes way more sense. Before, when I'd go up a mild (and mild might be exaggerating some) hill, or hit a headwind, I'd downshift a gear and my cadence would shoot up 10-15 rpm. Today it was more in the 4-6 rpm range, making it easier for me to keep a comfortable cadence and maintain my speed.

I do have a question regarding my front cassette. Now that I see what a difference a new rear cassette makes I'm wondering when/if I should consider replacing it. I noticed today that when I shift from the middle ring to the big ring it takes anywhere from 2-8 seconds to make the shift (with a lot of grinding noise during the process). I'm guessing this isn't normal, so is that a sign of wear? I obviously don't shift the front rings as much as I do the rear. In fact, with my new cassette I can stay in the middle ring pretty comfortably the whole ride. But just because I can doesn't mean it's the ideal , correct?

Anyway, you guys have been so helpful, and I couldn't be more satisfied with my new cassette!

Can't wait for tomorrow's ride!!