I am thinking about booking.com but it will change how Airbnb pays the fee - from guest to host - so I am not too surw if its worth it. 

It was very much like pay to play. 

I would then buy more properties and use that cash flow to pay off the 401k loan in time

What should I pay attention to in Denver and surrounding areas?

I have about $15k I have to pay back for school.

I would expect to pay under $20,000 for a three-unit property.

Leasing Management Program Overview The Leasing Management Program will involve the following activities: • Annual review of all units via the tax assessor database to identify potential "hidden" leasing situations. • Creation and maintenance of a list of all units/owners approved for leasing. • Creation and maintenance of a leasing waiting list for homeowners requesting to lease their units. • Creation and maintenance of a list of tenants' names and contact information. • Inclusion of tenants in the association website with "renter" level access. • Inclusion of tenants in the violation system, including sending notices to them when needed. • Regular monitoring of approved leases to ensure proper actions are taken at the leasing expiration and renewal dates. • Preparation of quarterly reports for the Board of Directors outlining the current status of the leasing program. • Coordination with the Association attorney as needed for enforcement of the leasing provisions. • Assessment and collection of costs for this program from the leased units by the authority of the Community Covenants, Conditions, and Restrictions (CCRs), $150/year.

The first floor is rented out to a seasonal business, they pay year round, $1000 a month.

The listing shows that it has the potential to cash flow around 5K per month after paying for the loan.

One of my properties cost me a little more, but the other two were less than what I was paying with foremost insurance.