Keep it moving, there are plenty of qualified tenants out there that are far less likely to be a pain.  

Typically, larger apartments and other multi units give a better ROI and have more room to breathe, when it comes to inflation and adjusted value, based relative to income (cap rates, etc).If you want to play it safe, and you don't have a threshold for stress/pain, then play it safe and just keep what you have.

We did one through HSBC, and it was a total pain, and we put 40% down.

As you’ve said, Denver has too many quality people looking for a place to live, there’s really no point dealing with a pushy tenant that’s obviously going to be a pain in the neck.

The buyers were not easy-going and made the entire process very painful.

I agree - It has been a gigantic pain in Ohio to get assistance - I've had to spend countless hours navigating the system. 

We plan to update the leases to clarify that stopped up toilets/ drains are the responsibility of the tenants.The restoration company was helpful in working with the insurance and repair folks as well.It a pain and a mess, but will be  fixed with a lesson learned.

Focus on setting up systems and procedures early, to avoid those growing pains as you add units.

I think there's still quite a bit of opportunity within an hour of Paine Field, the fairly new airport in Everett.

Don't do that, understand what buyers in your area want first you should be able to avoid this very painful seller situation if you do so.