I ended up doing the half last year. But I'm guessing I'll run Olathe. Although St. Louis is the same weekend and that is a really pretty course, especially through Forest Park.

A buddy and I were thinking about doing Vegas but we put off training too long. Plus it's about a month before my wife is due with our first, so I'm a little leery about leaving town. The crappy thing is that it's on a Sunday. Riding on a plane the day before a race can really dehydrate you, and if I flew into Vegas on a Friday, I would be EXTREMELY tempted to do a bunch of other things that might dehydrate me.

FWIW, I ran the Pikes Peak marathon... hmm... must be at least 12 years ago.

Once you get above the tree line, it really is mostly a glorified fast march with a little hopping from boulder to boulder for good measure. If I were given the choice today, I would MUCH rather run up Pikes Peak again than run down it. That's what really kills your legs.

I trained in St. Louis and found one long hill for repeats. The legs held up fine. There was no way to train my lungs for the altitude, though, short of buying an altitude tent for sleeping--so it did make the miles near the top significantly harder than normal.

Good luck.