I'm sure other members here could give you more in-depth suggestions, but I'll throw in what I know. A school of six cories would be great to liven up your tank. They're also good at picking up scraps of food in the substrate that other fish miss. If your boyfriend really wants a pleco, do some looking around for some sort of dwarf pleco. Clown and bristlenose plecos are some that would easily and comfortably fit in your tank. If my experience, Petco usually only carries the
Common Pleco, but I've seen a few others at Petsmart. Maybe if you have a store in the area that specializes in just fish, you might find one of the smaller variations of pleco.
As for the
Pictus Catfish, they can grow quite big and are very active swimmers, so the norm for them is 75 gallons. Upside-down catfish would be good for your tank, but they prefer to be in schools, so take that into account if you decide on those.
As for the gourami's, I don't know much about them, so I'll leave that to someone else. All I know is some are classified peaceful and some are semi-aggressive.
I hope that helps, good luck with your tank.