Bora Bora in French Polynesia. Serengeti, Tanzania. Phi Phi Islands, Thailand. All destination favorites of the folks who book the tours at iExplore. Take it with a grain of salt, naturally. It's likely to be biased because it's put out by a company promoting tours to certain places. And yet...it IS a list of great places.
What they say about Antigua, Guatemala:
"With more language schools per capita than anywhere else in the world, it is no wonder Antigua is a favorite stop on the gringo trail for solo travelers. When not studying, you can climb volcanoes, hike, go drinking, and visit with the remnants of the Mayan culture."
A friend of mine toured Antigua with his wife last year and he noticed students of all ages sitting on lawns in the front of houses practicing Spanish one on one. Presumably with hosts they were living with for the week or month while they went to language school. It's high on my list of places to go to learn Spanish.
Another friend, who I went to Thailand with, traveled solo to the Phi Phi Islands (pre-tsunami) after I flew home from our trip together. She raved about the excursion. She's a pretty outgoing person and that helps. But the Thai people I met wherever I went in the country were friendly and welcoming.
Santa Fe, New Mexico, another recommendation on the list, would be a great place to go to a spa solo. Eat Tex-Mex. Buy silver jewelry and belt buckles. Mix with the one-third Angle, one-third Hispanic and one third Native American population that lives there. Relax in the adobe splendor of it all.
I went solo to Santa Fe before joining a hiking and biking tour with The World Outdoors, which I think was called Roads Less Traveled when I went with them. I didn't love the group on that particular vacation, so I couldn't wait to be on my own.
There you have it. A few more vacation spots to ponder.