For English, are you looking for something that just teaches grammar rules or that also teaches writing like R&S does? Have you looked at Shurley, Easy Grammar, Michael Clay, or First Language Lessons? We're using R&S, but for grammar, I think Shurley would be my 2nd choice. I've never seen the others, but I know they're very popular (especially Easy Grammar).
I haven't used LLATL, but it's very popular among classical HS'ers I know (since you mentioned Classical Conversations). It's Christian, but not in your face. If what we're using weren't already working well for us, I'd definitely consider it. I've flipped through some at used bookstores, but not enough that I could give you a review. This is a good review, though:
Review of: Learning Language Arts through Literature It's definitely worth looking into if you're wanting a full language program rather than just grammar.
You might like BJU as was suggested for a boxed curriculum. Abeka is much different from MFW... very "school-ish", so if you're looking for something like MFW, Abeka probably isn't it. (I like Abeka, though. It's very rigorous.)
I have a friend in town who is using CC for her 3rd grader, and I think the only thing she has to teach at home is math (although she supplements science as well because that's her passion). Is that how yours will work? Are you really just needing to fill in subject gaps?