I wouldn't keep Angel fish in that size of a tank, they do best in 55gal+ and should be kept in groups of atleast six. Small tetras, danios, and barbs can work. Livebears like Platy, Swordtail, and Common Molly are very nice. I also wouldn't keep Dwarf Gourami, because they can cause problems, even BRYON talked me out of getting them. Honey Gourami would be much better, but like to be kept in groups because of their size( 2in max) A group of six or eight would be nice.
Angels can be in 29g tanks. They need a minimum of an 18" height tank. They DO NOT need to be in schools. They may school in the wild, but they are territorial fish. The only way that I would ever have 6 angelfish in a tank is if 1. I knew what sex they were and only got females and 2. I had a 150g+ tank. If they pair off then they will get EXTREMELY aggresive and might kill every fish in their sight. One would be good for a 30g tank. They won't be as aggressive with just one of them, and it is plenty big.
Angels ARE pretty, but they need 50+ gallons :) otherwise I'd so totally have one or two. or five.
Danios are fast interesting little fellas. They do good with most other fish. Cories, are a good bottom feeder with a group of 4 or more :) Guppies I will admit are so colorful, and lucky me they never bred x) other wise I'd offer you the millionfish
Like I said before, they need 29g tanks at the minimum. One or even two, if cories were the only other thing in there, would be a nice fit and well stocked.
I would still suggest cichlids, they are very intelligent and very fun to have. I love them, and would be great with schoolers like rasboras and danios that everyone are talking about. Even some of the dwarf rainbows would be a great addition as well.
Another note: Cories do much better in groups of 6. I had my peppered cories in a group of 4 to begin with and they were semi-interesting, but as soon as I added more they got more playful and happy. I would suggest a 6 min on them. And in that tank size I would suggest 8 or so of the pandas or juliis/false juliis. For the larger kind such as the emerald, peppered, and albino I would do 6 and call the bottom good, especially if you get a ram or apisto.