Always best to run with doubles in the Canadian Rockies or British Columbia backcountry, unless of course your objectives are set in stone, then you can plan ahead. I always advise doubles vs a single and tag line as well, in remote climbing areas, for obvious reasons and flexibility. If you do chose to take a single, you need to take a 70m. If a rap has been retrofitted away from doubles in the last couple years, we usually set it up for a 70. I don't even own a single 60 anymore. Many doubles typically weigh the same as a single and make for easier hauling amongst partners. Doubles are by far the safer option for those who are familiar with how to utilize them correctly. Good Luck and enjoy.