Hello again,
I'm not exactly keen on the guppies, although the idea of fry swimming around in there is appealing. Anything else, fish enthusiasts? Be creative if you wish, it'll spice things up a bit.
Shellies would be nice.....they're like the rams though in that they inhabit the bottom portion of the tank......but...they don't need as much room as a ram does....a pair of shellies might work......
Get some sort of layering going, Hatchets or something for the top, tetras for the middle, and cories for the bottom. That way you can utilize the height of your tank.
I see you have your heart set on a betta... but.. have you thought about other labrynth fish? There are a large number of unique gourami's that might fit the bill too... Off the top of my head I was thinking Croaking Gourami or the Sparking Gourami.
Both of these fish are small, full of personality and make noise.. Not your typical fish. They could add a lot of character to a tank such as this.