Conciergerie

If you buy the combo ticket with St Chapelle, it's only €5 more to add the Conciergerie, so if you're planning on St Chapelle then I would say yes, it's worth seeing. I enjoyed it - great building, lots of history. I was in Paris for a whole month so I tried to see everything, but if I was only there for a few days I'm not sure it would have been near the top of my list.

I like it in there - especially on a first trip to Paris. It's on the Paris Museum Pass... are you getting one of those? They're pretty handy.

It's a quick visit. Worth it in my opinion. No waiting (or not when I visited once in August). Close to St Chapelle. Included in PMP.

Ereddingius: I would not buy tickets exclusively to visit the Conciergerie; however, if you have the Paris Museum Pass, then visit as part of your visit to St. Chapelle and Notre Dame.

We thought the Conciergerie was a worthwhile visit on our multi-day trip to Paris. Good exhibits, lots of history, central location. Don't remember whether we combined on the same ticket with Ste-Chappelle. But I wouldn't base the decision on something like that -- if it's worth seeing it's worth seeing whether or not you get a "deal" on the admission. More a question of what interests you most in the time you have available. With a week or more in Paris, and plans to visit the Ste-Chappelle, Notre Dame, and other nearby sights, and my interest in history, I'd try to work it in. With a couple of days or more interest in art or shopping or whatever, then not.