For Martin Luther King's weekend, why not join a group of FTers in Singapore for SinDo. From the U.S., this is normally the preferred destination to maximize miles.

Use the multi-city function and check out routings via SEA, LAX, PDX, HNL and do the same on return. If you can add SLC, you can pick up a couple of hundred extra each direction.

You will not find this for $800, but a possible adder of about $400 will get you close to 25k with the good routings. You may want to also consider starting in the cheapest Florida city after a feeder flight.