I use it as a honeymoon spot, family vacation when the kids are young or the spot where secret affairs are carried on. I have a spa and a restaurant there. My sims usually treat themselves to a few massages and a yoga session. They usually eat out at the restaurant and I added activities to the national park. At the national park I have playground items for the kids, hot tub for the adults, the rock climbing item, horseshoe, thinking about adding the basketball, stuff for the whole family. I thought about adding a bowling alley to the park area but it is not really a social activity but I still might.
It varies what I do with the sims based on what kind of vacation they are having. Secret affairs usually stay at the cabin. Honeymooners hit the spa and restaurant. Family hit the park and possibly the restaurant.
