I have two Bolivian Rams, one German Blue Ram, and two Electric Yellow Cichlids in my community tank with Guppies, Platies, Mollies, Cory's, and Dwarf Gourami's.
I've had these fish together for several months, and so far I haven't had any problems.
I'm not sure how you tell if a fish is "happy" or not, but nobody's fighting, and they all look very healthy.