I bought some guppies at the auction on the weekend. They seem to go ok with the plecos. Pics are of blue-grass guppies, endlers and I dunno the varietys of the others as I am no guppy expert at all.
I am a guppy fan aswell, I like the endlers and ones that are just one colour. I think keeping guppies is benificial they seem to not bother my plecs and eat all the planaria and daphina that otherwise take over my plec only tanks.