Oh, happy day it is. I learned from WTS Books that The Spirit of the Reformation Study Bible is available again (hardcover, genuine leather, sample pages).
This is my favorite Study Bible. It uses my preferred translation (the NIV). It provides a good balance between accuracy and read-ability. The General Editor is one of my former professors- Dr. Richard Pratt. The study notes are extensive, and come from the Reformed Heritage. The ESV Study Bible which came out in 2008 has a leg up when it comes to charts and maps. But I think this Study Bible has a leg up regarding the translation (I know some will disagree) and consistency of theological approach. This is the Study Bible I recommend.
Cavman Considers 
I like the The Reformation Study Bible: (English Standard Version) Published by Ligonier Ministries General Editor-R. C. Sproul (or the NASB translation)
I haven’t actually compared the ESV Study Bible but I think all of them are a big help to anyone wanting a better understanding of the Word.
Yeah, all 3 of them are VERY good study Bibles. My preference is SotR. The NLT Study Bible also looked very good.
Yes, I have the DISCOVER GOD STUDY BIBLE NLT and it is great. Each of the 9000 study notes in the bible is designed to draw you close to GOD.
Could not find it on WTS’s site. I have seen a few notes from this Bible and have wanted to get one for a while but cant find it anywhere. I love the ESV study bible, and the Reformation study bible but want this one as well.
I suspect it is no longer in print. They have stopped production of the NIV 1984 in favor of the 2011. This great study Bible is one of the casualties.