SE Michigan (House on Zillow says it's worth $348k it's a 3br, 2 1/2 ba), semi finished basement.My house currently needs a new roof, new water heater.

He had to tear out the entire chimney chase on the roof, where he discovered a rotted area that was letting the bats in. 

What I had in mind was having a builder handle foundation, framing, roofing,electrical, plumbing, etc.

The only thing they share is fire sprinklers and roof. 

I was able to find a few good subs like electrical, landscaping, roofing, AC tech, foundation, yet can't find a good general contractor. 

Diversifying can be a risk if you don't know all the nuances, the learning curve isnt' as steep as STR, but if you are looking OOS, that presents new challenges.If STR is the path, are there places you like to vacation, that is always a good place to start.

Roof, windows, landscaping, carpets, paint job.  

, roofer to see if they are getting into the exhaust vent on the roof?

The last think you want to do is to put leverage on one of them and then need a new roof or furnace.

Its easy and cheap to insulate accessible locations like an attic and since heat rises and the sun beats down on your roof the attic insulation is probably your best bang for the buck when insulating.