This summer we're planning to build stacking enclosures for my leopard geckos so I can get rid of my rack. I was thinking of doing 18"x24" for the floor space, is that enough for 2 geckos?
That might be a little bit tight for two geckos. The key with cohabiting for geckos is making sure they have enough hides and enough area to feel separate and secure without having to fight over territory. Do you keep them together now?
That's about how much space is in my rack, I've got 2 pairs of females and 2 single males in it. The guy I got it from said 3 could fit in each bin but I tried and it seemed crowded and it got dirty super fast.
20 gallon longs make great tanks for up to 3 juvenile females. You can easily fit 4 hides in there, along with a feeding bowl or water bowl. Floor space is pretty important lengthwise, as it provides a better temperature gradient, and will also fit more hides. If you have a decent amount of width, it would be awkward placing hides all over the place.