Take a look at the MSR Hubba Hubba or, if you can find a really good sale, the Carbon Reflex 2. They are all-mesh tents, which means that in hot, humid weather you can leave the fly off when you pitch it, and have 100% ventilation. When it rains, you'll be well-protected, though condensation may be an issue.

Another good set of tents are the Big Agnes UL and SL series.

You'll probably get some recommendations for TarpTents, and should give them a serious look. I had a Rainbow, and liked it except for one thing: you can't pitch it without the fly (since the fly is 3 walls of the tent.) As a result, in August in Ohio (very hot, very very humid) the tent tended to heat up when you crawled in, and took a long time to cool down in the evening. They're great, light, well-made, affordable tents, though.

I'll stop now - you're going to have about 80 more posts to read.