I'm wondering if anyone has built a grape arbor/pergola this big? What dimension wood should be used? How close to each other should the support posts be? I want to use pressure treated wood or cedar...any suggestions?

I'm hoping to have a strong enough structure to support grape vines and snow...which we sometimes get a lot of in this area. This winter, not so much, but the last two winters...almost 100".

I have heavy clay soil and should probably sink the posts in quite a bit, but still want plenty of room to walk under the arbor/pergola without bumping into the grapes. I want to have a large table, maybe 3' x 6' and up to six chairs under the arbor/pergola.

I was thinking maybe four posts on either of the long sides, but I'd like to span the 11' without a center post. Does this sound reasonable? I want some cross pieces on the top with the smaller 1" x 2"s perpendicular to the cross beams. Will this be enough support for the grapes? I don't want lattice as it is too difficult to maintain and will rot with all the snow.

Any pictures or suggestions would be very appreciated. I have a contractor who will build it for me, if I supply the dimensions and materials list. He builds a lot of lake homes, but there aren't a lot of pergolas in our area. We have hot summers, but they're not very long and most people want to get as much sun as possible. I like shade :)