It's a guest room--don't overthink this. *I* would go to a paint store and ask for the most popular stock white. End of dillema. Do you have one guest who would use this room more than a few nights per year? Ask that guest for favourite colour to put on accent wall. End of dillema.

Good point. Thanks!

Mainly I’m just trying to avoid too many undertones.

Colors on monitors is unreliable. If carpet is golden beige, a pale blue could really brighten things up and is very calming color. A white would be cool and not very welcoming. Better lighting is in order too. Night stand with lamp or find wall mounted plug in sconce for nightime reading. Pretty ceiling light. I can suggest some blues if that appeals to you.