This is totally hypothetical but I'm crowd sourcing what other people think

We have a 4 bedroom house and 2 kids, so everyone has their own room right now and then we have a guest room. The guest room is mainly used by IL's, probably every other month they come visit for a long weekend. It's a small room, and we can only fit a full bed in there - they've already complained in the past that it is such a small bed (they sleep in a king at home, DH and I don't even have a king because our rooms are tiny!)

We're hoping to have a third, and always assumed we'd just have two kids share a room. But recently I've been thinking that is kind of silly because the guest room is unused / empty more often than not. I'm thinking we could put a queen sleeper sofa downstairs in our playroom and that's where they could stay when they come. While not ideal (because my kids wake up at 5am and IL's sleep until 9 or 10 and we wouldn't be able to use the playroom) I'm thinking we could just keep some toys upstairs when they visit.

If you had 4 bedrooms and 3 kids would you have everyone have their own room? Or would you keep a guest room that isn't used super frequently?