Knowing the gauge/weight of the yarn you need would help a lot. For charity items I think acrylic is good because it's generally sturdy and washable. That much cotton would be incredibly heavy.
Caron Simply Soft.. check the other lines they have too for colors.
http://www.caron.com/color_cards/cc_simplysoft.html
Red Heart SOFT..
Vanna's Choice
http://www.lionbrand.com/cgi-bin/yar...&pageLength=25
The Plymouth Encore suggested is a good one, too. They have dozens of colors.