In the process of paying for college for my three. Eldest is graduated and has a good job; other two are approximately college juniors.
The deal is I pay for everything that is required: tuition, room, board, books, fees, transport to/from, etc. If they can make a reasonable argument that they need X for the degree, I pay for it. They get to pay for extras: dates, cell phones, cars, pizza nights, movies, alcohol, etc.
We're doing it through a combination of UTMAs, 529s, ESAs, scholarships, and financial aid, as well as AP and IB credits. We basically saved since they were born, and my parents also contributed because they wanted to. We don't do loans; if we got to that point I would rather go back to work.
At this point it looks like I'll have some extra. The plan is ever changing, but if the situation holds, then it'll be a combination of going to a master's degree for one of them who is interested in that, or being distributed at graduation for them to put towards whatever - relocation expenses, house down payment, wedding, whatever.