Yeah I think they only showed up in Book1, Book3, The Alien short story and then in destroying angels. I can't think of any other appearances by the jockey in the old EU. I mean, I love those comics but the Jockey's never did anything for me.
The engineers in today's EU are almost too mysterious, nothing about what they are doing or have done is explained.
The idea of turning the jockey in ALIEN into the Engineers was hard for me to accept originally, but i've come around to it somewhat I guess.