I can't digest whey isolate/concentrate at all, so I'm forced to drink about a liter of skim milk every day. I'm also lactose intolerant, so that's a liter of lactose free milk per day. 2 cups pre and post workout (I often mix my creatine in the pre-workout milk too, with a tablespoon of defatted cocoa for a nice mental boost). Comes out cheaper than other protein sources, so I make do with the poor-ish protein:calorie ratio by cutting back calories in all my other meals.
lactose free milk is about the worst thing ever. they take out the lactose and replace it with cheap sugar. its processed even more then regular milk because to do that they've got to zap it even more. if you insist on milk go with goat milk as someone who is lactose intolerant. or be like me and just lose the milk altogether.