I live in PHX, so keeping water cold is always a plus. I recently purchased an insulated tube to attached to my camelback (the tube is made by them as well). I put cubes in my pack and that will keep the water cool for at least 3-4 hours.
I was having the issue of the first part of the drink being warm, mainly due to the water heating up while sitting in the tube. This new, neoprene insulated, tube really does the trick. Cold water all of the time. It was worth the $20 to me.
Another plus is the moldable wire that is between the tube and the insulation. It allows me to shape the water tube to fit my body, and no tube dancing on my face when the trail gets fun.