I think I got super lucky with my daughter...we decided to transition to milk first - so after her 12 month visit and approval from the pediatrician, we started putting milk in her bottle - she took to it fine (just didn't like it cold) {here's a tip a friend of mine did that worked well for her...she started adding a little bit of cold water to the formula so they transition to cold milk easier - she added a little more cold water each day...like an ounce each day with the room temp water}. We were always advocated that if she wanted water that it had to be in a cup and not a bottle, though, so she was drinking water and juice out of a cup as well...
We did the bottle to cup transition at 15 months (2 or 3 days after she turned 15 months) and went cold turkey - put the milk in her cup and said here you go..she did just fine - didn't need/want a bottle at night...I've heard other moms tell me their children still wanted a bottle at nap or bedtime, but mine was ok with just drinking milk and water in her cup throughout the day....we do have her milk in an insulated cup though, so it stays colder longer and she drinks it all day long (she prefers milk over water)...but my daughter still really isn't eating a lot of table foods, so meal time is still not an adult meal for her (she gets an oatmeal or breakfast jar in the morning, a 6 oz tub of yogurt at 5 pm - after her nap, and then at bedtime she gets a fruit or sweet jar food...the rest of the day she snacks on crackers and cereal) {if I let her have her way she'd eat cereal and crackers all day and that's it - nothing else...this is my compromise to her}.
Hope this helps at least a little.