We've recently gone off the bottle; we tried swapping out the kid's lunchtime bottle of milk for a lunchtime sippy cup of milk at about 12 months. Didn't go so well. The kid--who's been drinking water from cups for ages, wouldn't touch the milk at all; we gave up after a week of flatout rejection, only to find that we couldn't go back: the kid now refused her bottle, too. For another week, we panicked, making sure we weren't starving/dehydrating her with only two bottles/day.
But we kept at it, throwing a variety of sippy cups at the kid, no pressure, and then a couple of months ago we introduced milk at lunch. This time, it worked, and she started drinking milk out of a couple of her cups. Then we switched the morning bottle to a cup, and a couple of weeks later, we switched the bedtime bottle. She's never looked back.
The kid has been happiest with the simplest, cheapest cups around, Take & Toss cups with sippy cup lids from The First Years. They're small--4 or 5 oz.--and easy for her to hold and own, but that meant we had to refill them to get 8-9 oz into her. So my wife came home with these 10 oz. cups, which have straw lids, but which also fit the sippy lids. They're great, and we use them all day every day. (One big cup was slightly off, though; the lid came off too easily, so I took it out of circulation to avoid surprises.)
I guess you could call these things disposable, but you'd be a dope to throw them away; they last for a long time, clean easily, go anywhere...I prefer to think of them as losable, not disposable. You're not gonna stress over it if one goes missing at the park.
The First Years Take & Toss 10 oz. Straw Sippers are $3.99 for 4 at Amazon (and everywhere else, too)