Just got back from an Interrailing trip with my children, my youngest either slept in a bed with a bed rail, on the mattress on the floor, or in bed with me- depending on what kind of accommodation we had and what the space/layout etc was like. No way he would have been happy in a travel cot unfortunately!
We're doing a villa in September and planning on putting a double mattress on the floor and me and him sleep on that or alternatively, if by some miracle he's in his own bed by then, we'll put a single mattress on the floor and he can sleep there.
We are going on a cruise in May and will bring our redkite travel cot which he still fits into. But our room on the ship has a sofa bed as well as a king size bed so if needed he will just sleep in bed with one of us and the other one can sleep on the sofa bed etc as wanted to have options in case he didn't like being in the travel cot for some reason