I've got ~30 hours after they vacate to sheetrock, tape & repaint my living room ceiling before a wedding party checks in!)

Yeah, bland shades of white IS boring, but other colors will invite prospects to say "Iike the apt but need to repaint another color scheme". 

I'm amazed if you can get a tenant moved out, the unit repainted, and another tenant moved in with no rent-free downtime.

Currently the wall colors in every unit is WHITE in satin and looks if it hasn't been painted since the 70's so lots of scuff here and there and overall just looks like it needs to be refreshed so we're looking to repaint the units.My question has to do with wall colors.

We had it repainted by 9am.

If I repaint mine the buildings will not look cohesive and mine will look out of place.

A handyman might be great for fixing a leaky faucet, but when it comes to turning a unit, you need to coordinate multiple teams to repaint, clean, carpet, etc.  

Re paint it , add some trim , add some shutters .

Also, after the popcorn stuff is gone, how long should one wait before repainting?

Good Tenants (of about 5 years) asked if we could repaint dirty walls (we're not dirty at move in) and clean the carpets (cleaned at move in).