Given the success of my previous "core stability" based ski exercise program I got my trainer, Aubrey, to come up with a new one for me. Since I have a while between now and the Argentina trip I decided to try and rebalance a bit by including a little more upper body work and correspondingly cutting down on the leg stuff a bit. The last program was pretty much all core and lower body, now we have a bit more even coverage. I expect that I'll switch back to something similar to my previous program in June to give me two good months of solid leg work before the BASI Instructor course.
The new program has a lot of swiss ball work (it's a given that you're supposed to do all of these without falling off!).
Once off of the ball I have a collection of squats, push ups, multi-planar lunges, dumb bell snatches and, my current favourite "anger management" exercise; a one armed, standing chest pass against the wall. Basically you throw a 6-7kg medicine ball against a wall and really push through with the arm that does the throwing and rotate the shoulder to put lots of power into the throw. Then you catch the ball as it comes back at you and repeat until your arms fall off. Very good for getting some of my current pain and anger out - heaven help the guy if I ever happen to get within 4 feet of him and have a 6kg medicine ball with me ;)
As I said, I expect I'll switch back to a program that's more focused on "thighs of steel" before the actual trip, but this program is fun and includes a lot of balance work which I expect to be useful.