Everyone should see the Great Wall. It's amazing, but if you're adventurous, I recommend you finding a local who knows how to get you to the non-tourist postions of the Great Wall. My friends and I (one of them being local) took us on a 2-3 hour bus + cab ride from Beijing to this remote farm area and we hiked into the forest until we made it to the Great Wall. It's much smaller here but still, incredibly enjoyable to spend the rest of the day hiking along the Great Wall itself. Absolutely amazing.

Obviously, some of the hike was very dangerous and some areas were in ruin and very steep climbs, so I only recommend this if you're fit and up for the challenge. Either way, an excellent experience that I'll never forget.

I haven't been to the tourist area of the Great Wall though, so maybe someone can post what that is like and the pros and cons of that.