I'm not that fond of Plecos in planted tanks; so many eat or otherwise damage plants (sometimes unintentionally, as Plecos can be skittish an sometimes freak out for no apparant reason). Plus, on a personal note, I don't really like mixing bigger fish with smaller fish. I just looks unbalanced to me, though I suspect I'm in the minority here!
I'll definitely be getting a Pleco when I set up my new 55g Cichlid this winter (hopefully).
I'd get some Otocinclus cats; they are cute and fun and helpful (eating algae). If you have little algae, they should happily eat good quality (i.e., Hikari) algae wafers.
I also recommend Cherry Barbs! They are beautiful, friendly, energetic, and fun! I really love mine, and mine have been perfectly peaceful (never once nipping fins, even though they share a 20L tank with two Fancy Guppies).
With a heavily planted tank, some "plant-friendly" snails are nice (I have plain pond snails) as they help clean up dead plant matter, along with some smaller loaches to keep the snail population in check. Loaches are amazingly fun fish, too! I **ADORE** my two Salwnsis/Kubotai Loaches. They are TOTAL hams and have become the real stars of my 38g tank.
Shrimp, perhaps Cherry Shrimp or Bamboo Shrimp, might also be a fun and interesting option. Shrimp are fun to watch and surprisingly personable, and are nice as another type of clean-up crew.