A zippered pillowcase: it can be used as a pillow stuffed with plastic bags (to hold dirty laundry in between hand wash) or maybe a couple of shop bags.
It is great to house delicate laundry such as knit if it needs to be washed in one of those washers with steel drums with rough sides. I had one of those in a hotel, I once stayed in, for quite some time, the sides were so rough, I had to buy a couple of extra zippered pillowcases, at the local big box store, across the street.
It can be used as extra padding for purchases.
On a subject of laundry and padding: one small and one large zippered mesh bag to wash delicates such as Skookum Dog toys and leashes and ladies anti-gravity foundation garments.
A couple of Microfiber cleaning clothes like the ones sold at Trader Joes in the U.S which is part of the German grocery chain Aldi which might sell them too (sans logo but cheaper). Good for a lot of things, especially extra padding for stuff.
Japanese Microfiber hair towels are the best, the ones at Sephora are very efficient but heavy. I found a lighter one from Scunci, an hair accessories drug store brand.
After seeing a couple of Hotel Impossible episodes and reading some other hotel reviews, I will also bring my own washclothes.
And some alcohol wipes.