I know very close  what a roof costs, HVAC, water heater, windows, flooring, painting, remodeling kitchen, baths, lighting, electrical, plumbing, landscaping etc...

The larger residential unit just needs a carpet clean, possibly a quick paint, possibly some new windows (would improve the look of the front of the building) and a new tile shower surround.

Another is washable paint which allows you to wipe wall surfaces down with warm soapy water versus repainting everything.

Second is do you recommend we bring GCs out to estimate the whole project and compare or should we bring out subs for each part of the project (e.g. flooring, roofing, kitchen, painting)? 

Torn everything out to the joists, bleach, Kilz paint, then new subflooring and flooring (we used Kilz on the entire subfloor throughout the building to make sure we got rid of it).  

I love my line of work and can very easily put eyes on your project and lend insight on fixtures, finishes paint colors and even layout.To give you some insider info. 

I would get several cans of the low expand foam for doors and windows (brand name of 'Great Stuff' is just one of them) and spray foam complete entire window bay from top to bottom.If that stays dry thru a couple cold or wet spells drywall over this area with either drywall rated as moisture proof,,,mold resistant,,, or even use cement board tile backer(that should NOT harbor mold)...Paint to match

Flower beds maintianed, freshly painted houses and other signs that some folks actually take pride in where they live.

I'm planning to do some minor repairs, such as new paint (same colour) and replacing carpet with laminate in some of the rooms.

People are buying C class marginal assets for $150k/sq foot, putting white paint on old cabinets and marketing "upgraded" units for $50-$150 discount to the new class A.