My suggestion is to allow an admin to specify what random gametypes are allowed on a map-by-map basis.
For example, Map_A is best in HQ and SAB only, while Map_B is good for DOM, CTF and HQ.
Right now, if you set up random maps/gametypes, all maps in the list will have a chance to run all gametypes specified, which may not be a good thing on some maps.
I hope this is something that is possible!