It's going to be tricky to add fish with the angel already established. You'll see that it will attack most new inhabitants for the first couple of days.
If you want peaceful, look at a pair of ocellaris clowns, a yellow coris wrasse (not with clams), the banggai Cardinals, or maybe a larger goby (like a sandsifter). Your best bet is to window shop on websites like liveaquaria to see what you like, what fits the criteria you're looking for, and what fits in your budget.