I'm starting to play with the idea of taking the 20 gallon tall aquarium my boyfriend's parents offered me and transferring the current inhabitants of my 10 gallon to it. I've got my betta, 3 peppered cories, and 2 ghost shrimp in the 10 right now. I'd keep my argonite substrate and plant it really heavily. I'd really like to add a mid-level schooling fish that's very hardy that will do well in alkaline water. Guppies are a no because I've had really bad luck with them in the past and I don't want to take too big of a chance of upsetting my betta. He's very laid back for a betta though, and loves hanging out with the cories. They'll all school up at the bottom during feeding time some days and graze with Samuel leading the pack.
Does anyone have some fun suggestions?