Almost the end of the saga!
And a very happy ending it is. I was looking at beach cruiser bikes on craigslist the night before last, and found one I hadn't seen in my extensive research online before at all - a Marin Heart's Desire single speed. It was much less showy (no white sidewall tires even!) and less $ than the Schwinn since it was used. And aluminum, which I wanted for the anti-rust and weight benefits. I called the seller the next morning (yesterday) and it was still available. Went to see, rode it around some, and bought it (even bargained the price down a bit since it had been listed for a week)!
I absolutely LOVE this bike -- I couldn't wipe the smile off my face the rest of the day yesterday. And isn't that how it's supposed to be when you buy a new bike?! I've named her "Flor" (Spanish for flower). I haven't had a second to take any photos yet, but here she is in the Marin catalog: http://www.marinbikes.com/bicycles_2...hearts_06.html. She's in great condition, hardly been ridden, and lighter than the pink bike. She'll be perfect for Belize and even matches my DH's navy blue Trek Cruiseliner really well. They look like siblings!
The pink bike goes back to Performance this weekend. I don't expect any problems other than feeling bad about having to return it.
Thanks again for all the nice comments and support! :D