I think to have a betta work in a community tank, you have to have two things:
1. A tank that is 30+ gallons with lots of plants, low/no current spots, and plenty of hiding spaces
2. Relatively compatible tank mates
3. The tank needs to be stocked or understocked with fish close the the same size as the betta. NOT overstocked
Overall, I think for a betta to do well in a community tank, he needs SPACE and it's possible that any aggressive tendancies the betta may have could be accentuated by crowding.
A couple of weeks ago, Mark, our last betta, wasn't looking so hot. The only time he showed any real life at all was when someone came in the kitchen and talked to him. Mark reminds me a LOT of Jakers in personality. He can be a real monster towards other fish.
IMO bettas are very intelligent and I decided he may be very bored. I moved Mark into my 36g bowfront:
6 Millenium rainbowfish (very small, largest is maybe 1½", growing out before they go into the 75g)
1 Adult Platy male
7? Baby platys, largest is about 3/4" (going to the LFS once they get a little bigger)
3 Kuhlii loaches
3 corycats
2 "Ghost Shrimp"
2 Neon Tetras
2 Glolites
5 otos
The bowfront is very heavily planted with a LARGE Amazon sword, clover, riccia, hairgrass, rotala, apogenton, and bolbitis. Large piece of driftwood with lots of holes and two very large rocks, one of which weighs 29#.
The tank has a Penguin 330, kinda strong outflow, but I keep the tank topped because of CO2 and it doesn't give Mark a problem at all.
Mark has been looking good ever since I put him in there. He bothers no one except the "ghost" shrimp (fine by me! I hate those things) and spends all his time exploring. At first I was a little worried about the Milleniums, but they spend all their time in the current and ignore Mark totally. The tank is almost "divided" the way I have it set up. The left side has a medium current and the right side low or no current. He swims around both sides equally.
I think it was a good move putting him in there.
Roan