Do you always fix floor settling?

[Dave Charron]

I have quite a few rehabs under my belt and have fixed / leveled several houses that had some uneven floors.  I just bought a house (built in 1900) that has some uneven floors / settling issues.  Not too bad but noticeable.  I plan on rehabbing then renting this out.  If I fix all of it, I am probably looking at quite a bit of sheet rock cracking and having to repair most of the doors and cracking tile/grout.   I am considering leaving the floors the way they are and wanted to see opinions from other rehabbers on what you would do?