I went on two tours alone...I made life-long friends along the way! That's the nature of Contiki.
My advice would be to do as many excursions as you can. They are a great way to get to know your group, and they are always good fun.
14 000 ft! DO IT! It may seem like a lot of money at the time but it is worth every cent! Make sure you buy the video so you can prove it to all of your friends!