We're on that side of 30A. Our favorite things to do are:
Fonville press (Alys Beach) for coffee in the morning (sit outside - wonderful area to sit and relax -- bring a book to read). They'll probably start their Apres Beach get-togethers on Friday evenings soon, too. Wireless Internet inside and out.
Wild Olives (Rosemary Beach). Nice food there. I heard that you have to try their cheese platter -- expensive but someone said well worth it. I haven't tried it yet, but will.
Seacrest Cafe (Villages of South Walton): Good food, the carvel ice cream is very good if you go with kids. Wireless Internet inside and out.
Fountains at the Villages of South Walton: They light up at night and "dance" to music. Kids LOVE running through them and we LOVE watching the kids run through them. You can get something to eat at Seacrest Cafe and then bring it to a table and watch the fountains. It's so joyful.
Rosemary Beach: Sugar shak for ice cream and a few excellent restraunts. I enjoy walking through Rosemary Beach and looking at the architecture. If you're there during spring break or summer, you can go to free concerts at Rosemary Beach outdoors and free movies outdoors in the summer. Also in the summer, there's a market outdoors about once a month I think.
Deer Lake State Park (about 1 mile away): Absolutely amazing, stunning, unlike anything you've ever seen. The dunes are awesome. Free/no bathrooms/state park.
Shades: I like it -- new sports bar atmosphere -- wireless Internet access. I REALLY like the oyster po'boys.
Ride bikes and explore from Rosemary Beach to Deer Lake State Park.
If you decide to venture onto 98, you can explore Inlet beach and there are a few good restaurants right on 98 at the end of 30A (The Terrace, The Spicy Noodle). If you get really wild and want to go into Panama City Beach, we love Thomas's donuts. It's a good old fashioned donut shak-dive. Warms my heart just to think about it.
Most of the stuff to do is at the Villages of South Walton/Rosemary Beach. But it's all soooo close to Seacrest Beach. (Villages of South Walton, as far as I can tell, is part of Seacrest Beach).
That's more than enough to do on any vacation. We usually just go to the beach, pool, porch, fountains, Fonville, Wild Olives, Deer Lake sometimes, and then a few other places to for lunch or dinner.
Hope that helps.