Central America is a pretty good sweet spot for using miles because most routes never get discounted down to rock-bottom levels due to fare wars. There just aren't enough seats to most markets to cause that kind of competition.

We just finished MCI-ATL-BZE R/T. 3 tickets = 105,000 miles plus $145 (total) in taxes. Paid coach tickets (even 6 months ago) would have been around $800 each all in on any carrier.

So...105k = about $2200. Most of the miles were obtained in 2000 thanks to a series of mega-bonuses on DL Amex. (Anyone else remember the period of about 2 weeks where they offered a 50,000 mile sign-up bonus plus a series of threshold bonuses as well? ) If you have to outlay cash right now to get miles that you won't use for 5 years, that usually kills off the ROI completely. But in this case my cost of obtaining the miles was so unbelievably low that it was very much worth it.