Almost everything you need is already here!
Seriously, there isn't much for you to remember to bring. Probably most important, you'll need toilet paper, paper towels, dish rags and towels, and bath towels in your bag. Past that, food, clothes and toiletries. Your double bed will be furnished with all sheets, pillowcases and blankets. If you have small kids, you might consider bringing their sleeping bag to lay on top of the bed. The cabins are not air conditioned. If you have room in your vehicle, you might want to bring a small fan or two for the bedrooms at night.
Bug spray needs to be on your list, as does sunscreen and swim trunks. Do you have rain gear? If so, you should probably pack it. In the off-chance you venture out for a day trip and the weather turns, you'll be prepared. Sweatshirts are a must. It can cool off considerably at night.
Speaking of weather, if you want to know what it's going to be like the week you're at the resort? Check out this link:
https://www.accuweather.com/en/us/steuben-mi/49854/weather-forecast/2227794
When you look at the radar map, you're going to have to zoom in until you finally see Steuben show up. It takes about 4 clicks to get it there. Bear in mind, this is 4 miles away from us, but the best we can do for radar and temperature accuracy.
We do have life jackets on site if you don't have your own. For each person in the boat, there also has to be a life jacket. Do you have to wear it? No, but Michigan law requires it to be in the boat on the lake.
Former guests of the resort? Do you have anything to add to this? If so, PLEASE write a post! It helps us out, it helps other guests out, and can be invaluable when planning a vacation.