Keeping a "bunch of cichlids" is a very volatile subject. There are a few schools of thought and practice, both conservative and extreme. Some keep strictly species tanks, some have fish endemic to a certain areas of the Lakes. Some stock light, and still some, me included, stock the tank full. My 300g Malawi tank has well over 100 fish, including the catfish, Synodontis'(8 different species) and an adult dwarf giraffe cat. To say the tank is full might rank as one of the top understatements of the year. It is a very active tank.
The reasons for such diversity of thought is as complex as the fish themselves. Those that keep single species tanks do so to prevent any cross breeding, which will occur between some species. Also some fish, such as frontosas are rather large at maturity, they rival the size of a full grown oscar. Other fish, such as some of the haplochomines for example, are very ill tempered and are best kept in a species tank.
Those that keep "community tanks", a blend of this diverse family, do so to enjoy the fish themselves. They are a pugnacious, territorial, busy, full of personality and quite a colorful group. Most mbuna, at maturity, will be less than 6" total body length. This makes them easy to stock in higher numbers in larger tanks, you can put quite a few fish in a big tank.
Those, like myself, overstock our tanks to keep aggressive behavior, and the injuries, from the "battles" at a minimum. A "hospital" tank is still necessary. The philosophy behind such a stocking scheme can be likened to the fish being harassed gets lost in the crowd. And soon the chaser gives up the chase or finds another fish to spend his energies on. The drawback to such a scheme is the filtration must be high and must be efficient. I would think nothing of filtering such a tank 10x-20x an hour. my large cichlid tanks have filtration approaching 3500gph on one tank for example. Using external and internal power filters, canisters, and power heads to achieve such high flow. I do not use sump systems.
Many have a unique breeding habit in that they are mouthbrooders. The female will incubate the eggs in her bucal cavity providing a safe haven for the fry. She eats very little food during this time, so it is best to have a tank at the ready for her rehabilitation when she releases the young. Males are also very hard on the females during courtship. If the female is unreceptive, he could, very possibly, kill her.
Most cichlids and plants do not mix. The fish are, for the most part, herbivorous and great excavators. They constantly rescape the aquarium to fit their liking. This is why some keepers shy away from undergravel filter plates with these fish. There are modifications that can be made very inexpensively for those of us that use this filtration method and also keep cichlids. They may also eat you plants. If you are looking for a planted look, plastic plants are probably your only alternative. Rockwork, for most mbuna, is almost mandatory. Caves, nooks and crannies are the order of the day.
By selecting cichlids, you will have chosen the largest single group of fish in nature. So, your range of choices will be larger than your tank!! You, again, need to make a choice of exactly what you are looking for in your tank. I wish I had your problem. But, quite honestly, I really don't need another tank, let alone another cichlid tank.