Since not everyone has the rooms for each room to have a single purpose, if the guest room is the only place for it, I think put it in the closet, behind louvered closet doors. You'll need to think about how often you actually have guests staying with you and how inconvenient it would be to disturb them while doing laundry. I've seen washers and dryers in the master bedroom closet. I personally like to have the laundry closer to the bedrooms than near the garage. I think it could work if you don't have a lot of overnight guests.

I still think we need to see the floor plan

Not every guest wants to sleep in a laundry room. Look for other options that could take space from the guest room by building a laundry closet accessible only from the hall.

Yup, we found a hallway closet that could be turned into a washer dryer closet. Thank you all!

I dunno. I know someone who's washer/dryer is exactly that way - in a closet opening into the hallway. She HATES it. No room to do anything but throw the laundry in the machines and close the door. No space for folding, hanging or a hamper, and not much space for supplies. She says it got old real quick. She wants more space next time.