Paint the outside, painted the units, replaced carpeting, new fixtures...

If you have carpet consider a cleaning clause if you don't have one. 

Even in the best scenario you would have spent $1,500-$2,000 to update the smoke detectors and C02 testers, cleaned the carpet, re-glaze the bathtub, update any leaks and light paint and wall repairs.  

Get you some Kilz and strip out all the carpets.

Looking at my first property and there is a severely intense odor in the basement (concrete) and some slight orders on the other levels of the house as well (hardwood floors and carpet).

One I know is days on the market but I would like to know a strategy more in terms of the work needing to be done on the property.What is the typical rehab budget for a full gut versus a fixer-upper that needs some updating such as for the kitchen, bathroom, new carpet, roof, and/or driveway for example?

Pulled all the carpet up.

Occasionally someone left the kitchen/living spaces messy and I would have to do a bit of extra cleaning but not often.

partnerships get messy.  

It Depends.Potentially capital investments in the properties could have accelerated depreciation benefits (carpet, LVT, trim, appliances), while also allowing you to drive higher rents, thus saving on some taxes in the short run while driving increased values.