20g sorority into 37g community

[bastage]

So I have 9 CT females in a 20g currently. Well today I picked up a 37 gallon to take its place.
This is a tall tank at 30" long x 12" deep & 22" tall. So I suspect that the Betta's will stick towards the top for the most part & this will give them way more space then they had before. So what would be some good tank mates to put in with them. I anticipate a couple of orange mystery snails (a gal here locally has a tank full of them so I think I can talk her out of a couple as I like they way they look). I am sure I will need some other sort of Algae eater as well & shrimp met a quick end the last time I dropped them in with the girls so there out. So since its a pretty decent size tank should I stick to cory's or pleco's.. Or anything else for that matter. And what else can I have in the tank with the girls or should I stick with just adding more of them.

Also substrate will be silica sand & a mix of live & plastic plants to begin with (later to become all live).