Red that sounds like a great tank! I am so jealous that you have the Apistogramma macmasteri available locally. I have wanted a trio of them for forever! Rainbows would be great with them. I have rainbows in with SA dwarfs in my 70 gallon, and they get along great. Their colors also compliment each other very well. I have very hard water (pH 7.8) but I use
driftwood in my tank to soften the water a little bit. Both the rainbows and cichlids will appreciate planted tanks as well. Good luck with the tank, and don't forget to post pics!!!