Most people think male when they decide to get a betta, but the females can be just as pretty. My female betta is one of my favorite fish. If it were me, I would go with several female bettas of different colors instead of just one male. Actually, I'm thinking about changing my original plan for my 28 gallon and doing female bettas.
If you want more than one female betta, the minimum is 3, 4 being better.
The only thing I've ever kept with my female betta is an angel, cories, a plec, platys, and ADFs. They all do great together, and the bright orange platys look especially great with my purple betta. A lot of people overlook platys for something less common, but platys are super hardy, do great in most any water, and are great community fish. Having the bettas as the main attraction with a school of colorful tetras would also look nice, but I've never kept bettas & tetras together, so someone else may advise against it. Some tetras will nip bettas fins, but since the females have shorter fins, I would think they'd be okay.
Let us know what you decide!