We just returned from a vacation in Mesa, Colorado where my wife's grandmother has a cabin. The first day there it snowed a 4-6 inches giving us fresh powder to ski on the next two days. I got in one run on that snowy day during the short break in snowfall. I ended up running 20k (12.4 miles) in 1:40:50. It is very hilly up there and I could definitely "feel" the altitude. I haven't uploaded my garmin data yet but the town of Mesa, CO is at 5600ft and the bottom of the ski resort is at 8200ft. The cabin is somewhere in the middle, I believe around 6500ft. I ran in my New Balance 921s which are supposed to be designed for winter conditions. I was ready to be done as my right tibialis posterior started talking to me after about 90 minutes.
My advice for anyone traveling to altitude is to run based on effort and keep it easy for the first two weeks as most of the running effort will feel tougher than normal. It can take at least two weeks to acclimatize and even then it will take more effort to run the same speeds.
The next two days were spent downhill skiing. Both my boys went to their first ski school and did great. Matt did a day and a half of lessons and Micah did a one hour lesson and did multiple trips on the magic carpet with Andi, Clark, and I. The boys enjoyed the ski lessons and far exceeded our expectations. There were so few people on the mountain that the boys both had private lessons and we felt like we had the resort to ourselves. Once at the bottom we could hop right back on the lift for another run. It was pretty cold though, the temp at the top (9850ft) was -9 degrees at 9:00am!