If you want to grow live plants, you could plant a group of vals. The corkscrew ones are pretty. The pygmy chain sword could also be useful.

Dasheen

I'm really new at this but I have Java Fern, a valisneria (I think) and what was sold to me as a water wisteria. The water wisteria has a stem with roundish leaves every inch or so (i.e. it isn't grass shaped like the other two) and my betta often seems to sleep 'sitting' on one of the leaves. I read somewhere, maybe here, that bettas were the 'butterflies of the fish world'; he looks rather butterfly-ish perched on a leaf like that. You might get him something shaped like that. From what I see most fish stores have a pretty limited selection of live plants. I'd think live ones would be more comfortable; the plastic ones especially seem like they'd be kind of scratchy to something as small as a fish.

WW