What sort of plecos do you have? If you have sailfins or commons, you may be able to get away with keeping them in a 75 gallon but personally I find it to be too small for one, let alone two. They're also heavy polluters and definitely wouldn't be keeping the tank clean once they've grown a bit.
Are you looking for small schooling fish? A large group of rasboras, tetras, barbs or danios would do nicely in your tank, there are many species to choose from. You could also keep a trio of gouramis, a group of either small loaches or corydoras, livebearers, or possibly even an oddball tank. You may also want to look into doing a biotype tank, though that would involve sorting out plant species and decor as well as fish species.