So I have been looking around at backpacks trying to decide what to get. I am guessing that most of my trips are going to be 2 - 3 days.

One of the things that I just haven't gotten much of a sense on, is how big of a pack I need (roughly). I don't want to go around with a suburban on my back, but I don't want to go too small either.

I have been looking at packs like this:
http://www.campmor.com/outdoor/gear/Product___88681

It seems to be a decent size (maybe even a bit on the big side) and looks to be an all around solid backpack. Thoughts?
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A tent is a bad place for an argument, because when you are angry you walk out and slam the flap. How are you supposed to express your anger in this situation? Zip it up really quick? ~Mitch Hedberg