I have a feeling this will be a show that changes a lot out of town and in Broadway previews. Who even knows if the material will work on stage! I'd wait for Seattle until buying tickets. This could be a disaster or a pleasent surprise.
"wouldn't it be different for every show?" Yes it would but Young Frankenstein permired about the same time that Shrek will be this year. And I remember tickets were sold over the summer. and plus most winter shows the tickets are sold in the summer.