Use the ricemilk factory trick: add a pinch of vanilla to make it more palatable. My kids won't drink milk straight, but they love it (especially warm) with a little vanilla. (Their dad figured this out--he added sugar too, but I don't, and they like it well without sugar ... and since I use lactose-free milk, that's saying something!)
I cook with milk (lactose free, so I can eat it too). I make french toast, sometimes whitesauces, sometimes mac+cheese ;) ... and then there's the cheese on nachos (I'm not sure how 'nachos' are supposed to be made, but I use real, unscary cheese ;) ), the cheese on a tuna melt ... occasional ice cream ... we don't eat cereal anymore, but if your son does there can be milk on that ... and then like all the green vegetables have calcium (not that we eat enough of those, but I'm working on it ;)!!!).
But straight up, we almost never drink milk except vanilla-milk if I think they need a warm, soothing, non-chocolate ( ;) ) drink. They get one cup of juice at each meal and after that they can have water ... in our family, 'drinking' is about water content, and the whole milk-nutrition thing I'm working other ways.
PS I saw a report one time in a mainstream media (I can't remember even whether it was a paper or a magazine) that said that something in chocolate inhibits absorption of calcium ... so much for the 'chocolate milk' fix that is pushed at gradeschools! Like so many other things that kinda aren't surprising once you see them in print but go directly against the mainstream teachings, I've only seen that once. So, you'll have to decide with your gut whether it's true (feels reasonable to me--unfortunately, it hasn't cut down on my chocolate consumption much ; P !). Not that I figured you'd be doing chocolate milk anytime soon ... but if it comes up later ... when my oldest hit gradeschool I told her she could only choose the chocolate milk on Tuesdays and Thursdays ...
... oh, I guess that's another thing. As soon as the teachers expected her to and all the other kids were doing it, my oldest suddenly drank milk (at school) without even mentioning it. An, the power of peer pressure: do you have family/friends who drink milk straight? Do you? Perhaps your one year old could transition to real cups with vanilla milk or something ... the kids' dad and I both (for very different reasons) don't drink milk ==> no reason for my kids to!