Good looking tank! I like the bog wood extending out the top. I've seen Java moss growing semi submerged on bog wood like that and it looked gorgeous, come on give it a go. There are quite a few plants that would look great coming out the water there.
Rainbows are very active fish and generally need large tanks.
A Harlequin shoal would look great in there and they're small.
I've found taking pics at night with only aquarium lights on and no flash to yield best pics. You'll probably need to cover the light escaping over the top of the tank though.
I like the lily's and anubias.
Cool tank.