And there are some good to have items like granite counter tops, remove popcorn ceiling etc.Total renovation cost would go up to 10k if I were to do all of them but the rent increase I would see from previous rent collected is anywhere from 200 to 250 a month.Now, is there a formula to calculate how much one needs to spend vs rate of return in rents?

Stone countertop (granite or quartz) over linoleum 5.

You'd want fresh paint, flooring, cabinets, countertops, etc. at that price point. 

Kitchen will be new appliances, creation of an island, granite or quartz countertop, we may keep or replace cabinets and just paint them (they're in great shape and are original at 25 years old, seller was never home). 

Obviously people are attracted to brand new bathrooms and granite countertops but are there any other things to be aware of that have caused you to have a hard time, or a really easy time, getting tenants in your properties? 

You will also need to install cabinetry and countertops, and you may want to consider adding a small stove or oven if you plan to do more extensive cooking in the space.Finishes: Finally, you will need to finish the interior of the garage to make it suitable for habitation.

Countertops 3 or 4k installed.

Especially wood floors, cabinets, countertops.  

There are two issues to consider: control and financial structuring.Do you want to pick out the windows (black trim is all the rage right now), floor stain color, and countertops, or do you want to leave that to someone else?

Save the money for something more important like HVAC, countertops, paint etc.