You'll want a few more female guppies, at least two more. Otherwise, things would be a few groups of schooling fish, some bottomdwellers (e.g. cories or small loaches), and a few larger 'centerpiece fish, for instance, peaceful gouramis.
kulhi loaches are great as long as they have places to hide in the tank, which means they'll hide a lot and you wont see them all the time.
a group of tetras would look good. be careful adding so many female guppies else you'll soon be overrun with babies!! unless you're wanting to breed them you might want to consider getting a fish that would eat them up quickly, although most will