This is not one of the more active boards, so you might have to wait a few days before getting a bunch of responses. There are several current students and parents on this board, though, so don't worry.
I'm going to be a freshman this year, so I haven't personally taken any classes at Carleton yet. I have, however, visited three English classes. I also visited and interviewed at both Carleton and Kenyon before applying early decision to Carleton.
Both schools--along with just about all liberal arts colleges--are going to have great English programs. Both Carleton and Kenyon offer school-sponsored study abroad English in London, which was something that definitely interested me. If you're into creative writing like me, Kenyon likes to make a big deal out of potential fellowships at their literary magazine, the Kenyon Review, but I got the impression that since English is such a large program there those slots are pretty competitive. Carleton also has a literary magazine, and I believe you can check it out online, but it seems much more low-key than Kenyon's. Both schools offer workshop-type creative writing classes that have very positive reviews.
Check out the course catalogs at both schools to get an idea of the English department offerings. For me at least, the decision between the two came down to personality. I was simply a better fit at Carleton than at Kenyon. You couldn't go wrong with either of them.