I have two small angels in with mine and they seem to be pretty happy, infact the suris seem more calmer with the angels.
Suris are genrally bottom dwellers and do best in groups of four or more.
They also require plenty of open ground with a fine substrate as as the name Geophagus suggests, they like to sift through the gravel looking for food.
They have a tendancy to root around the base of my plants too, luckly the substrate is deep enough that the roots are weel rooted otherwise the plants would have a hard time.
They are my second fav cichlid after discus.