[JanS]

All of the above suggestions are great. I've also heard of people having good luck with White Clouds in a tank that size.
The only snag there is that they like the water a little cooler than the others.

 

[JanS]

I agree about the WC's being too active for a smaller tank, that's why I've never done it myself. Same goes for the Z. Danios - very active fish.

On a last note, if you go with a Dwarf Gourami, it would probably be best to nix the Betta since I've heard they don't play well together. Again, that's just hearsay, but better safe than sorry.

 

[JanS]

To answer your question about Cherry Barbs: I have a group of them (and they are beautiful), and I haven't noticed any aggession in them at all. I really dislike most other Barbs, but the Cherry's are way different. It could be interesting with the Betta though since they Cherry Barbs are so colorful and it might intrigue him - I'm not sure on that one though.

They would probably be okay in a tank that size, but they are sort of active too. Although on a last note, I Q'd mine in a 2 gallon since that was all I had open at that time, and they did just fine.

Let us know what you finally decide on. I'm glad to see you are really weighing your options.