I have taken a few ferries in my life so far, I actually really enjoy them. As a kid I was iffy on them
But getting to ride them a bit older I really enjoy them, and looking out at the water. In Vancover we took a big one, but camping me always had to take a smaller one to get to an island camp ground.
I've taken them a few times, yes. Once you get over the disorientation-- or once you acquire your sea legs as people with more experience put it--the experience is quite interesting. Something about traveling over long stretches of nothing but water, even though it's only for relatively short distances, is truly different from sitting in a car all day.
Yes, a lot of them. It was always SeaFrance or P&O on my way to France. I don't experience seasickness, I just find the journey very, very boring because there's nothing to do on them. Not to mention the rush back to your vehicle when it's over...
I prefer taking the Eurotunnel where possible, since it's so much faster and I can stay onboard.