Plecos are cool fish. I've got three of them:
1 x gibbiceps pleco - 3"
1 x Blue panaque pleco - 8"
1 x Sailfin pleco - 4"
The gibbiceps and blue panaque work on cleaning the glass, and the sailfin and my sucking loach (6") work on the rest of the tank
But what you have to look out for is if you but one of the non-common plecos, make sure you have the right water conditions. For example i wanted a gold nugget pleco, but cos my malawi need a alkaline water i couldnt get one (gold nugget needs soft and acidic water type). He said they can adapt but is it worth paying £30 for a fish which might die?