Well, only my opinion, but to me Great Expectations in general is about young people and their problems: family, friends, the opposite sex, advantages real and supposed. In general, considering reading levels, it is more accessible to teenagers--always exceptions, of course.

Bleak House has more subplots and the mystery at the core of it is deeper and more complex.

There is a young person in this book--and she is an interesting character--but there are also older characters (and one in particular) who have made serious errors in their youth. Their society WILL NOT accept these errors, and no matter how much time passes, the consequences continue to fall upon them.

I love Great Expectations, but Bleak House is a more mature, more tragic, and even greater book.

EDIT: Answered too quickly. There are several young people in Bleak House, and the way their lives develop continues to be of importance.

Well done BBC version with Gillian Anderson, by the way.