I think it depends on how you want to live after you retire.
I'll be 60 in July. I haven't given any serious thought to retirement, simply because I enjoy the people I work with, the job that we do, our place in the community, etc. It's fun. That said, though, I'm pretty sure I won't want to be going into the office every day when I'm 70.
My smokin' hot Puerto Rican girlfriend and I have discussed this. She's retired from NASA and her pension is, well, pretty fuckin' impressive. We've discussed moving from Florida, which I think is pretty much a given at this point. We're both just over it. I've got my retirement and investment accounts which should easily provide for us. If I choose to sell my companies on top of that, well, a life of never-ending leisure for me.
So, it becomes a question of where we want to live, house or condo, etc. We also discussed having a "base" and buying a Prevost motor coach and hitting the road. That would be okay, and would suit the photographer in me just fine. Diesel prices are gonna' have to come down for us to do something like that, though...