**Energy Efficiency Grants**: Look into local and federal grants for energy-efficient improvements.

Save the money, clean it till it shines, maybe basic improvements like a few new light fixtures or at least matching/bright lightbulbs, maybe a few new faucets, some paint touch ups and sell.If you’re hiring a Realtor®, they can tell you pricing in current condition versus pricing with a few minor changes.

Outside of jeopardizing a current property I own, the spread on this can't be worth the time or energy. 

I never pull permits for;  swapping AC, swaping fixtures (lights/fans/faucets), flooring, paint. 

@Don Konipol not out of the air, based on my own rental and a few hundred others we've done at Net Energy in 8 states.

The tenants know the mini split is their best bet for controlling temp on their side, but they do not want to not pay for the energy to run it and would prefer the gas gets used (gas is included in their lease.) 

@Natasha BradfordTo save your hard-earned cash and energy, I strongly suggest signing up for one of the many wholesale programs available.

Others may have had a good experience but we would have been better off lighting our money on fire to heat out our home.

Similarly for the master bathroom, I want to only replace the existing vanity with a new one, keeping the current light yellow tiles.

Without knowing your exact situation on time, energy, and capital it's hard to limit down to a market.