@Mark Miles I use Apple Pages for the printed guestbook I put into sheet protectors and combine with local maps/guides, then the free platform-based guidebooks on AirBnB/HomeAway/others for the digital versions. 

I find this metric easier to estimate "apples to apples" is a sense.  

This in some studies has been shown to outperform or at worst break even with buy-and-hold investing and is WAY WAY WAY WAY less involved, gut-wrenchingly exhausting, and fraught with those inevitable bad apple tenants.