I used one our vacation to Canada this year. We were staying in a cabin, and because we had stayed there prior I knew that there was zero room in the bath for towels and such. There was a towel bar and 1 hook, but since we provided our own towels I guess there wasn't a priority for storage!
I took a collaspable sweater shelf, like for a closet, with the larger shelves. It has velcro on the part that wrapped around the rod in the bath. That way all the clean towels and stuff didn't end up on the back of the toilet or the floor.
I wish I had had 2 or 3 more! The bedrooms had 1 shelf with a hanging bar below. The collaspible shelf would have been great for t-shirts, sweaters etc. And I was thinking that these will be great for other vacations too. We always run out of drawer space and with one of these shelfs, all four of us could have one. And we never use all that hanging space anyway. Sort of like using the over-the-door-shoe holder. Which I have slowly, over time purchased ones to stay with the suitcases, so now I'll have to get some the sweater shelves too!
I purchased mine at Big Lots for $5 or so, but I think Dollar Tree or Deals may have them. Of course, Wal-Mart and others have them too, but much higher price. Because I thought of this at the last minute, I took the one out of my closet but it was simple to remove, pack, use, vacation and then put back.
Actually if you wanted too, this would make for a great pre-travel staging area for all the clothes too! Just add clothes to the shelf, then transfer the clothes to the suitcase, pack the shelf and then reverse once you settled in at your destination!.