Village of South Walton is a good location in Seacrest Beach. It is across from High Pointe, has some restaurants/shops, and sits right next to Rosemary Beach.
They have studios all the way up to 3BR units. Some units they call 'flats' which I believe do not have kitchens so I don't think a unit like that would work for a longer term. I think those units just have a small refrigerator and microwave but I'm not 100% sure of that.