i agree on petunias but i disagree on the lack of scent. mine smell wonderful. a friend came over and was standing near them and was wondering what the nice smell was and it was the petunias.
also i recommend the Wave petunias. limited colors but you don't have to pinch the dead blooms to promote new blooms, it does it on it's own so you can be more lazy. however, they LOVE water so you must keep up with this in order for them to look their best.
also, you could probably try a dwarf crape myrtle, as long as it's getting direct sun light (that's how you get all the blooms). they're drought tolerant once they are established.
also if you don't mind a non flowering plant, go for a snake plant. they're pretty hard to kill. do well with water and without it, with heat, with cold. not sure what's up with that, but when i read that, i was like hell yeah and mine is doing just fine.
i'm all about the plants that let me be lazy because i'll kill them otherwise.