I suggest leaving the cotton at home. Once cotton gets wet or even just damp, it gets heavy, loses any insulating ability it might have and takes forever to dry (what's the last thing out of the dryer?). When the experts say "cotton kills," they aren't exaggerating a lot. My daughter once got into the early stages of hypothermia hiking in temps in the lower 60's in soggy jeans (the grass and brush along the trail were soggy from previous rain and waist-high). Since she kept quiet, it took quite a while before the rest of us realized she was becoming incoherent. We had to stop early, strip off her wet clothes, stick her in her sleeping bag and fill her full of hot cocoa! If she'd been alone, she wouldn't have been able to help herself.

Synthetic fabrics are far lighter and, when wet, usually dry from your body heat in 15-30 minutes. Look in the athletic (not outdoors) departments of big box stores like Target, KMart, Wallyworld for nylon track pants. The one backpacking area where cotton does have a place is in hot deserts where a cotton knit shirt can be doused in water and used as your own portable swamp cooler.

You have a lot of redundant clothing. Most of us carry only the amount of clothing we would wear all at one time in the worst possible conditions we could expect for a specific trip. The exception is an extra pair or two of socks. Rather than taking pajamas, sleep in your hiking clothes or in your base layer. You can lighten up quite a bit by taking less!

Check out the articles on the home page of this site, left-hand column for lots of ideas and sample gear lists.