Unless things have changed in three years, the cafe on top isn't much, just drinks and snacks. A nice reason to sit nevertheless.

We were at the cafe last year and it did sell paninis for lunch that were quite good. We went with our kids and they really enjoyed it, but we were also with our Context Rome guide as part of our Vatican tour. She had a lot of interesting things to tell us about it. My daughter particularly liked the Pope's bathroom. No reason for him to live austerely even if he was hiding out.

We took our kids there last year. They enjoyed it. We used the info in our guide book and walked aroud at our own pace.
we ate ice cream in the cafe & enjoyed the view from the top.
If your kids are young they may enjoy the little shuttle train which you can board outside the castel & it takes you around the Vatican City.
It was also a great way to spend time before an early lunch & our visit to the Vatican Museums when the lines had gone.

Do you have to purchase a tour of the Castel Sant' Angelo in order to visit it's rooftop cafe? Or can anyone go there?

No, you can only gain entry to the castle with a ticket.

Neopolitan..... thanks for the link! Forget where I first heard the story. However, I DID see Caballe in the role. And no way would she have bounced back... because she stepped off the parapet VERY gingerly -
El husband and I still chuckle about it.
As far as the cafe.... we just had a glass of wine.... where we thought Tosca jumped.

My husband and I enjoyed it a great deal...wandered on our own. A picture I have at work is my husband at a table (one of our many cappuccino breaks) looking thru the stone arch with St. Peter's in the background.

Thanks, again, everyone for all the great info!

Dina