The biggies that you don't always see (read expensive) for me in CO are stable soil/foundation/water intrusion, aluminum wiring or out of favor fuse panels, hvac if not replacing, sewer scope in most older neighborhoods, roof (which will need to be brought to code (shingles, ice dams, re-sheeting maybe) on the sale usually if it's older). 

It's in a safe stable neighborhood (B class) and has long term tenants that want to stay.

Purchase Price: $600,0002 family - average / slightly above average existing condition Total Monthly Income (Rent + Parking spot):  $4,400Mortgage + Tax: $3,300 Water / Sewer:  $900 a year, $75 a month Insurance: $1,200 a year or $100 a month Utility expense paid by me: $50 a  month, rest paid by tenants Lawn / Snow: $50 a month average Unexpected Maintenance:  $100 a monthTotal net monthly cash flow of $725, Cash on Cash Return of 5.2% (based on down payment, closing costs, and assumed $15,000 investment in units to upgrade)Not a staggering return but seems to be cash flow positive and should be stable. 

Also, lenders typically only count rental income that has been stable for two years towards income they will consider when deciding how much mortgage you can cover.

Stable renter it appears.

Jeff,The difference is the definition in zoning - office is just as you suspect, it can be a business that operates out of a space but does not sell the product to the public from the space ( you can not walk in and shop), Retail is someone that sells a product or products from that space where you can walk in and buy something from the shelf.

I am financially stable in my everyday life, but I don't have a chunk of money to put down.

The east side tends to have clients that are a lot more financially stable.

We give higher points on our screening if their income is 28-31% of income, we've found that to be our sweet spot of high enough to pay but low enough to stay put awhile.We look at a lot of other thing sin screening, like address history, landlord references, smokers, how often they move, how stable their income history is, if they have a bank account (most don't), criminal, etc.

A 1031 exchange has a very short shelf life and the commercial RE market is also very hot.