Bring either sleeping-bags or bed-linens (and a blanket or such) and a pillow. The ‘windows’ are screened with lowerable outside flaps depending on the weather. Some years, it has been really cold; others, it has been hot and humid.
There are toilets and showers (hot and cold water, of course) and sinks in each cabin. Apart from your Dopp kit, you should bring several towels since nothing seems to dry in the woods.
Bug spray with DEET is very highly recommended for those days when the mosquitoes are around. And they are always around.
Sunscreen is also highly recommended, for general use – but especially around the pool area.
A small plastic poncho could come in handy in case of rain.
Don’t forget to pack any medications that you take. The Health Center has a refrigerator to store insulin or other medications. Red Cross certified CPR/AED/First Aid folks will be on-site. There’s an AED on site.
A small flashlight is useful for navigating the roads and trails. (Extra batteries!)