How much space do you guys like to have past your feet in your sleeping bag? I went and tried out a few at the store the other day and the lady there said to have at least a couple inches of free space at the bottom of the bag. The one I am looking at I can either get a 6'0" bag or a 6'6" bag. I am about exactly 6 feet tall and 175 pounds. The 6 foot bag seemed to fit ok with just an inch or two of space past my toes. The lady said that I should definitely go with the 6'6" bag but that seems like a lot of extra space to have. So again, how much extra space do you guys like to have in your sleeping bag? Thanks.