I recommend low-set metal bed frames. They're a bit to climb out of, but the shorter legs means less rocking. Here's the one we use at home and it has survived three years of group sleeping and group hanky panky with no signs of wear. Also they're inexpensive enough that you're not breaking the bank replacing them.

https://smile.amazon.com/gp/product/B01M1SC9DS

For mattresses, memory foam. NEVER use a spring mattress or a boxspring. IKEA's slat bases are way more durable in the longterm than a boxspring.