Thanks for the great suggestions everyone!

Paris is definitely on my short list, as are Venice and Hawaii.

I do find Singapore an intriguing options as I have never been.

I love the beach but I worry that if I went to a beach destination alone I wouldn't interact with anyone the whole time. Knowing myself I would end up on the beach or by the pool with a book the whole time, which while relaxing, I think it would get a bit lonely. I've been leaning towards a European city destination if only for the fact that I would get out to visit museums and see the sights that I want to see without impatient and bored kids.

Would any of you travel to Istanbul alone?