As someone who has been looking for cabins down in western Wisconsin, I can't recommend enough doing Pay-Per-Click (PPC) through Google. There is no one bidding, and you could probably bid a penny per click. Are you familiar with Google Adwords? Boulder Junction looks to have some PPC ads from VRBO as you mentioned, but Google may favor your ads more since it's specific to the location and not a run-of-the-mill aggregator.
Also, throw your information into the Google My Business https://www.google.com/business. It's free. Your contact information, website url, and description and map pinpoint will show up on a Google search.
Pretty much any area is nice. Downtown is 20 minutes from the beach. Don't go further inland than downtown though.
Destin is nice but the traffic and prices are horrible.
One of my friends is retired and has a place on Air BnB.
It's 10 mins from downtown, 20 mins to either Pensacola Beach or Perdido Key. It's on the bayou and he lets you use his kayaks!
Good luck. There's lots to do!
Couples resorts!! They are all over Jamaica, are 18+ (I was 23 when I went and I was the youngest person on the resort with the next youngest person being my husband who was 26 at the time and then after that it was mostly people in their early 30s and older) and are absolutely wonderful.
I wrote a whole review about Couples after my time there in 2010. You can read my review here - Couples Sans Souci Review