You'll get a feel for the age of the neighborhoods, the vitality of the commercial buildings, the ease of location, the closeness to jobs.The markets you're describing are more linear, and usually have lower capital appreciation.

Realtor.com describes how it works as part of your sale:“It tells the real estate seller you’re in earnest as a buyer . . .

However, this is not specific legal advice to you, just an opinion based on the circumstances described.  

We like the short-term rental idea because we could stay at the property ourselves when we want - summer break, spring/winter breaks, etc.Our budget will be right around $1M or less ideally, and we would like a short distance to the ocean.How likely is it that we could find a property as described above and have it cover or come close to covering the mortgage? 

I like the location and the price is 650kFor mixed use properties as you describe (and I'd assume is located on SW 10th St.), I'd recommend that the residential units fully cash flow the loan as my experience is that mixed use properties are tougher to finance as most lenders tend to prefer one or the other and something in the middle gets more difficult.For example, and granted I don't know anything about the area/neighborhood, I would expect this property (https://www.realtor.com/realestateandhomes-detail/111-NW-Har...) to be easier to finance than the mixed-use property you mentioned. 

Sorry, I guess it's a little difficult for me to describe since I'm not a financial expert familiar with the terminology.

However, this is not specific legal advice to you, just an opinion based on the circumstances described.  

Alas, this scenario didn't last very long, as you would expect in a free market capitalist society -- new money flood in, more STRs in supply, property prices increase, STR incomes decrease, until a new equilibrium is achieved.Nowadays, the word STR is being used to describe both the property and the business.

Etc etc.Easy living is the perfect way to describe it.

The fact that you described this tenant as "a good tenant of 5+ years" is what I would focus on.