We (me, my wife and three daughters - ages 7, 6 and 4 at the time) moved from central Iowa to western Washington 5 years ago. I found a job that was a better fit (and has grown into an almost ideal job), offered 20% more pay, and in a part of the country I'd always wanted to see. I grew up in Ames, went to ISU, then got a job in Marshalltown. In high school we took some nearly cross-country trips and I did a foreign language trip, and I knew there was a lot of the world I still wanted to see outside a 100 mile radius from Ames. The biggest thing I miss is going to ISU games. More than being close to family to tell the truth, but we do a lot of Skyping to keep up.
Editing to add: we were in a unique situation in that we were already homeschooling our kids and my wife worked online from home part-time, all of which we've been able to continue seamlessly after moving. If the kids were in public school, or too much older with well established friends, or if we were dependent on my wife's job that wasn't able to move with us, we probably wouldn't have moved. Now that the kids are established here we don't think it's likely we'd move back until all the kids are out of the house at which point the winters will probably keep us away. Also, all my closest friends from Ames High moved away for or right after college so I didn't have a social life keeping me here.