Synodontis catfish usually mix well with cichlids; a group of petricola or a single eupterus would do well in a 75.
Thanks for the suggestion, its something I hadn't thought of. I am guessing that Synos would probably shuffle a lot of sand and mess up my plants though.
Mike, your weenies are adorable, just as weenies should be! We adore ours, though I had no idea that a dog could be so bossy. I am more of a big dog person, but when you have a small home you have to compromise a bit. A Dachshund definitely carries a big dog attitude around in those short little legs!
I think plecos are the kind of fish that are usually peaceful, but when you make them mad, LOOK OUT! So, IMO that's why most fish leave them alone.