Dwarf Lily? Mine is thriving so far (I think, honestly it is hard to tell as I know nothing about plants), and I believe a lily will grow until the pads reach the surface of the tank. It is a fantastic plant for a betta as they love to rest on the pads that haven't reached the surface yet. Red root floaters are also beautiful and pretty easy to care for, although I hear they hate surface agitation.
My Wendtii isn't doing that great, but it is a crypt so is probably sulking due to the environment change and with any luck will regrow soon.
Hmm, this gives me an idea to do a whole tank planted with dwarf lilies, oh how fish/aquatic plant keeping is addicting.
Cabomba may also suit your needs as it can just be pruned when it gets too tall, mine is doing well right now.