A bit more on the altitude, not that anyone has asked. But these are some notes and maybe I'll blog it one of these days. And no one will read it there either!
Vigil's "Road to the Top" has a good summary, although that is now some 25 years old. Still relevant and a good read.
There is a slight (noticeable) difference at about 1000 meters, below that it's hard to tell much. Here's how you might break it down for training purposes--not talking about extreme stuff in the Andes and Himalayas.
Low (little or no effect) - 0 to 1000 m
Lower-mid (noticeable effect) - 1000 to 1800 m
Higher-mid (probably the best zone for training and living) 1800-2500 m
Higher - (gets harder for sustainable training) >2500 m, and especially more difficult after about 3000 meters (you just don't recover well).
Time for adaptation from lower to higher
Your EPO productions kicks in within hours, and the effect can last for up to 10 days. So a short stay can have some effect for a bit.
But if you really want to get some measurable benefits for both altitude and hopefully when you return to sea level then 3 to 6 weeks is needed. And the effect can last for up to a month if you've been at altitude for like 6 weeks.
It takes 6 to 12 months to fully adapt. And there is some evidence that those born and raised at altitude respond better.
What's the best combination?
Been pretty well established for the past 20 or 25 years that live high train low is the best, and there are a few places in the US where you can do that pretty well (Sierras and N. Arizona in particular), with Denver/Salt Lake regions also being pretty good because you can live at 2000 m to 2500 or a bit more and be within an easy drive to 1500-1600 m within a half hour.
Live high - train high works with some caveats. As mentioned recovery is more difficult. And the ability to train hard (fast) is very challenging. A compromise might be to at least get down to lower elevations for speed sessions. And there are a few work-arounds such as doing some speed training on a slight downhill.
Live low - train high is somewhat controversial (e.g., you often see people here [letsrun in general] post that it's worthless, and that you must Live at altitude for at least 6 weeks or you are wasting your time. Those folks probably just got it in a book and don't know. I'll posit that yes, you can get some benefits from live low train high, but only if you are consistent. A one off ski weekend in Summit County, CO (ca 2800 - 3000 m) may have a small effect, but it won't last long. But say you get up there every week, 1 or 2 days, for 10-12 consecutive weeks. Yes, you should probably get an increase in oxygen carrying ability.
Live mid - train mid - that's almost as good as live high train low, but you need to adjust your training some, with recovery, intensity, and speed work. You can't fight it, just have to learn to roll with it.
I've tried all sorts of combos, and the one I've been at the past few years has worked best: live pretty high but still moderate (2300-2400 m), and train at 1600 - 2000 m. Training is sometimes arduous (esp. at 60+ now!) but feels so great on those few weekends a year I can get to sea level!