The Great Wall of China!

I should be going on a trip to China in April 2011. Here's a link with the itinerary.

Anyone done anything similar? I won't be able to bring loads of gear but I think I can manage a bit!

Looking at my gear as it is, I'm planning on upgrading to FF before the trip. I'm thinking a 17-40 is a must. Since I've got plenty of time to plan and save, what do people think would be the best gear to bring?

You must like walking up hills.
We were there in July and as predicted, it was hot. April should be better in that respect.
We slept the night on the wall at Jinshangling and then walked to Simatai. Awesome !! Apart from the ever-present hawkers, being on the wall (nearly) on your own is great and well worth doing.
I don't know that I'd want to spend all that time trekking on the wall, but that's me. There is so much else to see, do and experience in Beijing/China.

I took a 40D, 50 1.8, 17-85, 70-300, 580EX and a Manfrotto 190XProB in/on a Kata 3n1-20. I don't think I'd have missed the 70-300 or the flash. I took all that on the wall. Get a bag/pack that carries plenty of water.

Other than the wall, be aware that it will be hard to get good shots of the tourist sights unless you can get there very early. There's more than 2 billion Chinese and it seems like they all want to go to the Forbidden City on the same day as you.

Steve.

17-40 +FF =Win!!!
I wouldn't bring too much especially if you're going to walk for a bit of the walls distance. Also keep in mind the some of the stairs are very short so don't lose train of thought you don't want to fall and damage your gear. I went in 2002 (I know long time ago) but probably not much has changed just make sure to not lug too much around and bring some water!!!! Do you what section of the wall you'll be walking?

17-40 will be great, and your 85mm since its not big or heavy. You can probably live without a higher zoom (your 50-250 won't fit on a FF and I don't suggest lugging the 100-400 around), but if you splashed out on a 135mm f/2L you wouldn't regret it.

Flash also probably not needed, but bring a light monopod - there's a lot of places with lanterns at night that can give great shots but you'll need longer exposures. I say mono- rather than tri- because you've probably never seen such crowds outside a mosh pit.

With the itinerary you plan, I would travel light. We've just returned from Beijing and took a day trip to MuTianYu which is one of the sections you'll be trekking. It was the highlight of our trip. At the entrance, there were heavy crowds but as you moved away, the crowds thinned and then disappeared. Also, the weather was cool but once moving, it was fine (early April). We spent about 3.5 hours actually on the wall and it is a very good workout. I lugged a tripod with me and ended up only taking a few shots with it. Instead I took a lot of hand-held panoramas (it was a bright and sunny day). I note that Heavenly Stairway at Mutianyu is the most strenuous climb - it is quite a climb but my kids managed it okay (with a lot of encouragement). You do seem to be covering some big distances though.

A 17-40 on a FF would be a good option. There's some great open wide views. I took and used a flash to give some fill for sunlit portraits on the wall. If I went again I'd leave my tripod. I took a 70-200 f4 IS and used it for some long distance wall shots. It's a lot lighter than a 100-400 though. Hope that helps.

My advice is travel light. As Stirfried suggested you have probably never experienced the crowds you will experience in China. If you are traveling by train at all, space is very limited (especially for luggage). If I was you I would take an all rounder lens (24-105), UWA (17-40 or maybe a 12-24), and if you really want a tele then either the 70-200 f4 as suggested or maybe even a 135f2 and a 1.4TC. As all these lens are f4, it would not be a bad idea to take along a 50 1.8 for inside temples etc. Of course if you can go wider and faster on the prime i would do so (35f2 or 24/28)