Hi - I'm not sure what rides they have open, but we were at DW (for the first time) in June and my son who was 8 1/2 at the time had a blast! I would say it's worth it...do they do a combo with Hershey like during the regular season? That's what we did and it was even better!
You get in free today (11/19) when you donate a toy between 3 and 8pm. We are headed there later this afternoon. 1 toy per person for free admission, see their Winter Wonderland page for more info.
We went last year and it was lovely. Very cold but lovely. The kids had a lot of fun. There was a pre-teen with us that enjoyed the lights and the festive mood.
I have to say if you are close by it is worth it. I guess it depends on how "old" the 9 year old is. Are they very "teen" like already or still a kid?
If "teen" like perhaps not.
We were there tonight with a two year old and an eight year old. It was crowded because it was the free night(with the toy donation) but I really did not think it was that great, we were there 1.5 hrs and both dh and I were glad we did not pay. I think Hershey is much better.