You might want to consider a larger species of dart frog like
Dendrobates tinctorius 'Suriname Cobalt'
or Phyllobates terribilis or P. bicolor
They are larger dart frogs and have a lot of personality, make VERY interesting pets, care for their own tadpoles (most of the time), and are cheap to maintain as you would just need to make one or two fruit fly and/or bean weevil cultures every 10 days or so to keep a small number of frogs.
Tree frogs can be quite boring, I have a group of red eyes, I've had White's tree frogs, and some others, and they have always been very, very, very boring (I always end up selling them cause they are so boring).
If that's your thing, then cool, some people love them. Red eyes recently got put onto the endangered list so you won't see too many more around in the next few years, so if you can start breeding them then GREAT.
Dart frogs are just interesting, diurnal, very active, always visible if you get a bigger species, beautifully colored, easy to keep (tree frogs are harder to keep than darts, if you have the right setup).
Plus it also gets you into the world of plants, there are lots of neat plants you can put into vivariums, even glowing mushrooms!
http://news.nationalgeographic.com/news/2006/10/photogalleries/glowing-fungi/