The ultimate travel accessory is a monogrammed cosmetics case. You'll use it each time you travel, and it's handy to have it monogrammed in case you're staying in a French country hotel and you have to share a bath.
This one from Pottery Barn is very classy:
This one from Whitney Caroline Designs is fun + perky:
For the ultimate monogram - appliquéd - from Leontine:
For a simple, classic look, try Carolina Clover:
And for the gentlemen, Orvis has got you covered: