I found the best holidays for a singleton were activity types. For example, I've done a rail tour of India, a week on a yacht off the south coast, a flying experience week based at Sheffield University, even did a couple of dinghy courses. Most of my companions were also on their own. You soon get to know each other.
After the divorce, I took the sprogs on a couple package holidays. Big mistake, they were alright playing in the pool or the sea. Me? I was 'billy no mates' Hated it. Then I discovered a company that catered for single parents. Both the sprogs and I then had ready made companions.
Now the sprogs are older I'm looking again at activity holidays.