So you're in Beijing and you want to see the great wall. Well there are about three parts of it within a couple hours' drive from Beijing. On the advice of previous travellers, I went to Mutianyu, a popular but not overly touristy part.
You can get there through either organised tours (often available through your hotel), taxi, or private tour. If you go by taxi, be careful not to get ripped off.
I took a private tour, which cost 900RMB for three of us. The driver spoke fantastic English, great for asking all those questions about the area and culture.
The best thing when you get there is to take the cable car up, walk 1.5 to 2km to the right, and either take the chair lift or toboggan run down. If you go up on the cable car, you can go left, but once you've seen 2km of the wall, you've seen it all.
You can climb up the steps, but it's hard work--trust me, I did it, as the cable car was closed for winter maintenance when I was there. It must have been 3,000 to 5,000 steps to get there, and more when you're at the top.
Word of warning: all the stalls at the bottom offer lots of gifts and food for $1; however, they cost more than $1--it's just a way for them to get you to their stall.