In preparing for our small group, I reread one book and read another on the book of Hosea.
Love Divine and Unfailing: The Gospel According to Hosea by Michael Barnett is a well-done book bridging the message of the Old Testament prophet with the gospel of Christ. Barnett does not take the prophetic book sequentially as much as topically. He does a great job of connecting the crises in the life of Hosea and Israel to the finished work of Christ, in which all the promises of judgement and life are fulfilled. While not technical it is informative on the text, and it is also devotional, providing encouragement that our current state is not "final" but that I will be perfected in Him. This was an enjoyable read, and a good entry in the "Gospel in the Old Testament" series.
Hosea: The Heart and Holiness of God by G. Campbell Morgan was an unusual find. Amazon and CBD carry few books on Hosea. This is published by an unknown (to me) publisher. It turns out that this is actually
freely available online. I bought it on Amazon and was expecting something a little meatier size-wise. But it turns out to be a great book of 12 sermons by the incomparable preacher. He is mostly on the mark, delving into the word and expositing the message of Hosea for Hosea's time and for ours. Occasionally he bases a sermon on one word ("Canaan" vs. "merchant" for example) without significant support, but overall a great book on, as the subtitle notes, the heart and holiness of God.
I also read most of Matthew Henry's commentary on Hosea (always good) and bits of Calvin. Calvin's was unusual in that it seemed to also be transcribed sermons.

For our study we used Dale and Sandy Larsen's bible study from IVP. Great bible studies are hard to find, and I suppose that balancing exegesis and practicality is always a tension of preparers of group studies. The "how do you think the prophet felt when..." kinds of questions rarely seem valuable to me. This study has some of that...
Nevertheless, the Larsen's do a game job of making Hosea accessible and practical. The questions usually helped our group to focus our attention in specific areas. As leader I used them as a jumping off point and added my own questions based on my further studies. I think that what I missed (having read Barnett's book first) was the relentless return to the grace of God in Christ that is the ultimate story of Hosea. The practical story of Hosea's call to love Gomer and to redeem her echoes throughout the balance of the book--in some places louder than others, but always there. At times the gospel seems dim, yet it is always there, and needs to be seen.
As a note, I started the study with an overview of the history of Israel and Judah and the key societal situations during the time of Hosea, the two calves, and the reasons they were set up, and a brief geography lesson. Among other sources, I found
this to be very helpful from a historical standpoint.