One thing I still can't really figure out after playing this quite a bit is how to tell when upgrading your base will actually be of any benefit. A bunch of the upgrades do things like increase max profits, etc. The problem is that as I understand it, there are thresholds for that which also require a certain unknown amount of reputation or you're just spending money for no reason.
As an example when I bought the stage upgrade that doubles max profits, initially the girls weren't earning any more than they did before but now they're definitely earning double. I've seen similar things with some of the other upgrades where I buy the upgrade and it doesn't really seem to increase my earnings at all for awhile.
The biggest upgrade I find myself wishing for is something that reduces energy use for the girls each night. Even with clean sheets and the max garden upgrade the girls seem to get tired relatively quickly. The only way I know of to mitigate it is really just to train the crap out of them to max out any energy/mood related talents they can get and increase their max energy.