We had 4 adults each with our own suitcase/bag and our own toiletries and we had plenty of room. Not like at home-level room, but definitely plenty of room.
One thing to be aware of, when the sofa is made into a bed (at least if it's the pull-out bed...I don't know about the flip over-style sofa), it will block all the drawers and cabinets below that counter when it is out. We found that out the hard way and had to life up the bed long enough for me to get my stuff out as I'd claimed those drawers. Even when I moved stuff the next day, There was still enough room for all of us without having to share or feel crowded.
I think from reading on here it seems to depend on how much you packed. We had a day outfit and something for the evening for each day as well as swimwear, etc.