I have a similar tank running so I'll share my experience so far. I have a 55 gallon stocked with 4 angels, 2 dwarf gouramis, 11 black skirt tetras and a bumble bee catfish. The tank has been running for 5 months. I can't speak to long term compatibility issues, but so far, so good between everyone.
The gouramis are both male so they like to chase each other around the tank and "duel" with their feelers. They also charge each other a little and generally despise the look of the other gourami. My tank seems large enough to avoid any serious problems. They blow off their steam and go back to their business.
The angel fish are still young. They do minor territorial behaviour and ram their fellow angels from time to time as well as the tetras.
The black skirts nip at other black skirts all the time in a quick circle maneuver. They occasionally nip the angel fishes long fins. (I had red eye and red serpae tetras previously and they were extremely fast and nippy towards the angel fish)
My guess is 2/3 of the time my tank is very lazy with fish relaxed and dispersed to all corners hovering. 1/3 they are swimming around. I would classify my tank setup almost as semi-aggressive, mostly between their own species, with no issues so far.
Good luck on your tank selection!
Bump: PS. I got black skirt tetras because I read they are a schooling fish (which they are), however 90% of the time they are not schooled. They like to disperse the maximum distance from each other and end up in every corner of the tank with 3 inches between each fish and they just hover there all day. They usually only school when they feel threatened which is when my lights switch off and on and during water changes.