You are basically going to find the two extremes, and little inbetween at the State facilities. Your typical RV sites will either be what I call "schorched earth", and less than pleasant (for my tastes), or little-to-nothing, limited hook-ups with only a central dump station. Power is "iffy", and the same for water, though it can be close by.... - these are the places where I usually am found.
Private campgrounds likely combine more services.
As for things to do, the Adirondak Nature Center up at Paul Smiths is really a fantastic way to kill a rainy day, and the nature trails and outdoor exhibits are pretty nice too. As you get into the area, you are going to find it is pretty sparce for "urban activities". Sitting back and watching the day go by is an Adirondak way of life. Lots of hiking, paddling, fishing, biking, etc. Little shopping, etc. unless you go on trips to Lake Placid, Lake George, etc., which are good day destinations.
The area is just awsome!