if you dont get a male betta (don't, unless you want a tank of dead fish, or to buy another tank) gouramis are fine in a 10 gallon - i have them there, peopla say that it might be a bit on the small side but then - look in a fish shop + think about what they live in then!
You can't judge what fish to buy from what an lfs keeps in its tanks. You have to remember that most of these fish are only there for a short time.
I think a pair/trio of Dwarf Gouramies would be fine or you could go with 4-5 Honey Gouramies.
How many female Bettas are you moving to the 5G tank?