Nice tank! The rainbows look really happy with lots of room to dart around in.
Do you have a pic of the lobster? I am curious about him, does he try to catch the fish? Does he eat the plants at all?
Do you have the actinic lights on in the last few pics? I would expect the tank to be alot more blue.
As for additions, you should try for some stem plants, they are really great for filling in gaps in the aquascape. You could try easy stems like wisteria or rotala rotundifolia. You could also try some Alternanthera Reinecki to give a bit of red flash.
Also, cheers to upland brewery! I lived in Bloomington for 5 years and that was my beer of choice while there.