This is certainly not a Hilton-specific issue, but as others have said, it often depends on your situation and on the property.

I've got two young kids who would rather sleep in a bath tub than share a bed (I'm exaggerating here, but to make a point ). I've been either booking suites/larger rooms that have sofa beds and then requesting rollaway beds, bringing my own extra bed (air bed now that the youngest is too big for a folding cot), or in some cases booking two rooms. The really awesome part of the Hilton portfolio is that you can actually book confirmed connecting rooms. And because of how premium rooms are priced on points bookings, it is often cheaper or almost the same cost to get two rooms. I do, however, wish Hilton would specify if rollaway beds are available/allowed in room descriptions like Marriott does. It would make some of this easier.