I spent several weeks in Nicaragua, cycling about the country and attending a Spanish language school in Granada. Nice people, and very inexpensive, about 1/2 the cost of Costa Rica.
Thinking about going back soon.

TC knows what s/he is talking about, regarding the availability of reward travel. If you find workable award seats, snag them immediately.

I strongly recommend Nicaragua! I spent all of August (primarily based in Diriamba) attempting to reconnect with family. The town is very laid back and welcoming. The people are friendly, everything is super cheap, the weather is perfect (breezy but with warm temperature), and it is a great location to commute to Leon, Managua, and all the amazing tourist spots and scenery that attracts visitors year round.