Well, I lead a small group of 5 married couples.
I'm not sure what you want to focus on.
What we really try to focus on is improving our marriage and community service.
We are currently doing The 5 Love Languages and our most recent study was "When Sinners Say 'I Do'"
I've read the 5 Love Languages before and I wish I had read it when I was first married. It would've spared 20 years of confusion! :)
When Sinners Say 'I Do' - I thought this was pretty good. It definitely got my wife and I talking and while I had an issue with one of the author's opinions it didn't diminish the overall value of the study.
This book is 10 chapters, we covered 2 chapters a week as a group. The final chapter was especially hard hitting as it focused on caring for a spouse in the final stages of life. Something my father is currently going through (mom has been 12 years with Alzheimer's) and my mother-in-law went through.
We skipped discussing chapter 9 as a group (talking about sex). It just didn't seem appropriate for our group.
EDIT: I also wanted to mention that any study guide out there has flaws. But those flaws can spur some good conversation. The study guides are just a starting point to get conversations going within the group. The real value you'll get is from hearing how other couples interpret what they read in contrast to how you viewed things.