I may keep having babies just to have the stroller to carry everything! But yes, absolutely bring it for a 5 year old. My oldest is 5, almost 6, and when we go in May we will bring a sit and stand for him and the baby. Every other trip until now, including 2 while he was 5, he had his own stroller. It kept him cool and rested, he could sit and have a snack or drink while we moved, I always knew where he was, I could store all my gear, he didn't get a sunburn, it saved us from many meltdowns.l.I could go on and on. Worst case, you bring it and leave it in the room, but it comes in so handy on the long stretches, and then you can park it and walk around each smaller area before going back to get it.
If I could put DH in a stroller to cut down on his whining, I would do that too.