I have heard good things about Oak Park, Forest Park and Berwyn, but beyond that I don't really know where to look.  

I would like to have a new central air conditioning system installed for my 1,800 SF  100-year old single family victorian-style residence in Oak Park, IL. 

Full time mechanical engineer in the oil and gas industry, part time investor chipping away at my cash flow goal number - primarily from a passive role lately.  

It was expensive and tune consuming, but the results are nice, painted outside, natural oak inside The so called energy savings that will pay for the windows over time is a fallacy.Add a good storm window to a single pane one, bronze spring, and the R value is almost the same.This is a lot of work.

2ndly what about having oak flooring on stairs leading off a downstairs in another color of laminate? 

For instance:New oak door=$300100 year old oak door=$3!

Which is a factor where, let's say a bag of chips cost $1.00 for 10oz of chips.

After tons and tons of submitted offers I finally landed a sweet deal in Sherman Oaks, California for $250,000.

If you are looking to be close to downtown without the downtown prices MUCH better city services, check out Cicero, Berwyn, Forest Park, Oak Park, there are some other areas nearby with good multifamily housing stock. 

Maybe use it as a bargaining chip.