If I have a beach house that is booked heavily in the summer but not in the winter, I could have a house in the mountains that would still be booked in the winter to offset the lack of income from the beach houseCons- Harder to manage from far away- Would need to stay familiar with laws in each areaAny thoughts?

2.How to run the hot tub without guests for a few winter months (avoid headaches)?

Rehoboth is probably a little better than Bethany for the off season, because it has more year round residents and activity, but rentals are still pretty dead over the winter. 

It will be interesting to see if this trend sticks around now that we are out of the winter slump and buyers are moving again. 

In the winter you can pull them out and put them in your garage or something to stay warm.

Less choices in the fall/winter, but then again, we're not worried about where to put the tv, or what color the carpet is :) 

Not sure the best way since in summer electric will  be higher and winter gas.Would we list those yearly amounts in the lease and just use the last fully occupied year?

Your grandmother should retain ownership and pass it onto you to benefit for the step-up in basis, avoiding a significant tax burden upon its sale, especially if she isn't already liable for estate tax.

Now if you have a place that is short term say in summer and mid-term winter because you get a significantly higher rate in one season for STR that makes sense.  

But those stocks don't need a water heater replaced in the middle of winter, or a new roof, and require no additional capital from you to exist.