I currently have 3 divided 10g NPT...I think fish appreciate the effort of real, live plants. The look on some of Thai bettas that come from small jars to me and I acclimate and then plop them in a jungle...they love it!
For this reason alone, I will plant their homes. Divided tanks look bad, aesthetically, but I will always plant them because it's for the fish, not our house decoration. I have come up with a solution, though....for the male fish as well as aesthetics: I have begun tying moss to the plastic grid divider....make it as thick and covered as possible since moss is such a slow grower. I got directions online on how to make a moss wall that you can hang up in the back or side and it will eventually cover that wall like furry wallpaper. It was easy to see how same idea can make the divider have furry wallpaper :)
This way, it limits, until it obscures completely, the line of sight for the 2 bettas.
You could also plant a row or two of a tall plant like some of the larger valisnarias to make the divider/fence more obscured....
I agree with aokashi: start with ghost shrimp...they have a better chance of surviving being locked up with a predator than some of prettier shrimp like RCS Red Cherry Shrimp (or their orange, yellow, or blue cousins)...all of which start at $1/per shrimp and up! You probably want to start with at least 10...
Snails can go in, in my opinion, to tank now....they are pretty hard to kill...might want to put 1 or 2 pellets in per day or every other day...because I don't know how much microscopic food you have available in your tank at the moment...or you could give them some lettuce/spinach/blanched veggies...up to you.....just remove uneaten food everyday.