I like the Neon Orange or Neon Green Cories. These are not dyed, but a natural band of color. I have seen them at Ocean Aquarium in San Francisco. There are several species of spotted Corys- C. julii, C. trilineatus and others. A cory of a different color: C. adolfoi
Other bottom dwellers: Small to medium size Loaches. Y. sidthimunki are great little fish, and slightly larger Loaches such as B. striata are good. I would avoid anything like Yoyos or similar Loaches, they are too big, and may eat the smaller fish.
Roseline Barbs will get big enough to eat smaller fish, so I would skip Threadfin Rainbows. I have a Pearl Gourami, and Melanotaenia trifaciata 'Wonga Creek' with my Roselines.
A larger school of Rasboras sounds like a good idea. Then if a few do not want to be part of the school, there is still a good sized group to watch.