Hades' family are always on the Limp pilow alert watch:

Best solution: email in advance "Inquisitive minds wish to know : does the hotel provide a pillow menu?"

If not,

Pending restrictions travelclass & destination & duration & hotel class:
travel with an extra suitcase with travel pillows.

My Emergency solution : prop & stuff pillow contents into the pillowcase, double knot pillowcase, to secure contents in place
Kids solution: firn pillow part of sofa or chair, wrap in bath towel and use for sleep
same if there are any backpacks or books
S/O's solution : remove pillow from pillowcase, fill it up with the stacked bathrobe / folded towels from bathroom

As a result, never moody clouds and morning grumpyness at the Underworld household