How much time to give for Eiffel Tower Summit?

Are you saying you have booked an 11.30 entrance to the tower. It just depends. You can get to the top of the tower and back in 30 minutes if that is all you are interesting in seeing or do. Be generous -- allow an hour. But if really interested in the tower and want to see and comprehend the many exhibits on display, you could take three or four hours. How much time do you normally spend in museums or other similar sites?

Our experience last summer was that it was about an hour from our booked time to when we reached the top.
The booked time is when you can get in line for the first elevator.

You will wait in line again for the second elevator.
Also, if you plan to take the elevator down, you wait in line again. :)
I would plan 2 to 3 hours depending on how much time you want to take pictures and enjoy the view.

the Summit isn't the end - you have access to the 1st and 2nd floors, too. there are places to eat, adirondack chairs to hang out in, places to shop, etc. So if you want to just hit the summit and go back to the bottom, a good hour. But the other floors are cool too.

Thanks. I’ll give it a couple of hours. If I gauged it by my son’s trips to museums we’d be there until they kick us out.

vegaschristmas,
Don't underestimate the time you may wait in line for the elevator to the top level, or the wait to go back down.

I know there are stairs to the first level. Are stairs an option to the top?

No stair options to the top for visitors. And I would guess that if their were, one would have to be in terrific shape to go up that way. And the traffic jam with people going up and coming down would probably be unpleasant.