The best idea is to make a good plan and use more low-power access-points instead of several high-power access-points. Plan for 2.4Ghz and 5.0Ghz since every device released this day will support it and within now and 2 years you will NEED to have it.
For 2.4Ghz plan your spacing and channel usage accordingly, say if you have 3 access-points on a floor and have multiple floors, do it like this for instance:
6 1 11
11 6 1
1 11 6
6 1 11
11 6 1
1 11 6
For 5Ghz, use as many channels as you need. Less channel overlap is best. Use 20Mhz channels, no 40Mhz.
Meaning, don't overlap your channels, both horizontally and vertically. And again, put your access-points in low power mode and deploy more to cover the area you need. A neighbour access-point should only just hear the next one, not full signal if you put it on high-power with high-power antenna's. Clients will also not know which access-point to chose if they receive multiple access-points with about the same power.
As said above, Mikrotik does not have a ready-to-go solution for this. Neither do they have 2.4Ghz AND 5.0Ghz solutions using a routerboard out of the box. The rumors are that they will be releasing it soon though (could be a week, could be 6 months).
Oh, and do
NOT use a QRT-2 indoor.