29 gallons sounds pretty good.
I think you could probably fit around 15 cichlids in there.
With cichlids, its usually better to overstock as they are aggressive fish and they like their territories, the more fish in there, the better as when two starts fighting, another one joins in and they sorta get distracted, the aggression is spread out more.
Another thing you should know about cichilds is that they like hard alkaline water and they like to dig. I would suggest no plants in the tank as they will uproot them. The substrate should not be sharp as they like to dig through it and sharp substrate will cut their mouths. I suggest using coral sand and make it fairly deep. Put in LOTS of rocks so that they can have little crevices and hiding spots and caves and each of them will make some parts their territory. Try using rocks that will raise the pH. Driftwood usually lowers the pH and itll kinda spoil the nice rocky look. However, if there is enough rocks, they should counteract the driftwoods pH lowering effect. Most well setup cichlids tanks will be very rocky and will usually look very white and may even appear to be a marine tank to those new to cichlids. The advantages of cichlids are mainly that they are very hardy fish and very colourful too. I would suggest getting a good filter for them too and getting another pump to circulate the water as they like that.
Hope you listen to my advice, but don't take it as the gospel truth, consult your LFS for advice on setting up the tank as well.