I have a tank of mostly live-bearers, with guppies, platys, mollies, and 5 neons, and down to 2 danios... I've found the neons to hide much of the time, with the guppies & danios most active, followed by the platys and the molly, tho the last 2 types spend much of their time hiding... I would suggest fish with similar activity levels. also, my live-bearers explode in population every few weeks... A betta might be g ood population control.
If you want a ram, keep in mind that it is semi-aggressive, and while they tend to be more peaceful then other cichlids, they can harass other fish quite often. I have my ram in with my gourami, and he holds his own pretty well. If you do get the ram, make sure everyone has ample hiding spaces. My ram is pretty territorial about his cave.
Tetras are a fun bunch, and will often make use of the middle-level of the tank. While mine hide often, I think it's a function of my active guppies and bullying danios.
Let us know what you end up with!