Top/Bottom Unit - Best Strategies to Address NOISE!

[Reid Sealby]

Hello BP Friends! 

Last summer my fiancée and I bought a house outside of Denver where we live up top (currently) and rent out our basement on Airbnb. The basement is a completely separate unit blocked off by doors we had installed. It was built in 1960 and tends to creak and moan as old houses do. With basement guests, we can hear some muffled noise - nothing crazy, but some! And, when we're downstairs, you can hear footsteps and creaking from up top.

In the near future we plan to move out into a new home, and rent this current house as 2 units (top & Bottom). Initially, we thought we would Airbnb both the top and bottom, but some other friends who Airbnb both units have had negative reviews about the noise, mostly caused by the top guests, affecting the bottom guests stay. There are 3 Bedrooms Upstairs and 2 Bedrooms Downstairs. All that being said, the strategies we're considering are: 

1) Airbnb-ing both units, but limiting upstairs occupancy to two guests (still allow 4 downstairs).

Pro: Still optimizing revenue with STR, noise mitigated by limiting upstairs guests

Con: Miss out on opportunity for up to 6 guests in 3BR upstairs.

2) Long-term rental upstairs, STR in basement. Offer LTR Tenant a below-market rental rate, under certain agreements to limit upstairs noise since we will still be running an Airbnb business downstairs. 

Pro: Fixed income from top unit, respectful upstairs tenants

Con: How to find a Long term tenant who would agree to this kind of agreement?

3) STR entire home as ONE unit. 

Pro: Allow for up to 10 guests, high revenue potential

Con: One unit revenue > two units revenue, higher likelihood of parties/damage/issues

Sorry for the long post - I would really appreciate some insight from STR hosts with top/bottom units as to the best way to go about maxing revenues and avoiding bad reviews from the noise! Thank you all!