I fully agree that it is smart of landlords to treat great tenants as if they are worth their weight in gold.

@Tal Shachar  While you can do a lot to older windows replacing ropes and ensuring weights are in place to open and close your issue will be liability due to lead paint. 

Also, the easiest way to avoid gaining weight is to avoid food. :)   Your formula is not how it works, and I cannot give you a better formula, because it really is complicated when it comes to depreciation recapture.

Now we have raised the rent a little but we have to figure out whether to raise it a lot to reach the new market rate or gradually and leave more on the table each month.

Hand them printed application and credit inquiry form on that you write you need w-2 and year to date paycheck, names/ages of all occupants, breed /weight of pets, bank statement attached.