Here's just my humble opinion regarding step 2 review books:
I call it my "essential 3 books"
1) Prescriptions for the boards: This is a great *review* of all the specialties. It is a rather lengthy book, but it is a great starting point to refresh your memory, and build a *basic* platform for the rest of your review.
2) Crush the boards - This book is *packed* with key concepts and info. If you haven't set up the basics by reading "prescriptions", this book will not make as much of an impact. Don't overlook *anything* in this book.
3) NMS review - The questions are a great way to assess your studying, but don't get too hung up on some of the questions - I encountered several questions which prompted me to roll my eyes at the scope and context in regards to its validity. Concentrate more on the explainations in the back, rather than if you got the questions right.
Those are my "must have" suggestions.
The only other book I enjoyed enough to suggest is "Usmle Step 2: Mock exam". It was good to do for timed tests, but may seem quite familiar, since it mirrors the concepts outlined in crush the boards(same author wrote both books) - *However*, it is a great way to see if you mastered the important concepts in "crush the boards"
And my last suggestion would be, after ample time for studying, just find a book to do questions, questions, questions until test date.
As for time for studying: that is very individual, but I would suggest no less than 1 month worth of studying - Don't get roped into the "step 1 - study for months, step 2- weeks, step 3 days" routine. It could prove lethal.
Last comment: (sorry to bash a series of books, BUT) Blueprints series is not worth the paper it is printed on. The only book worth even looking at is the OB/GYN book.
Blueprints:
Surgery - Terrible - God Awful, enough said
Medicine - Way to simplistic/Limited topics
Peds - Covers minutia/obscure topics in peds
Psych - Maybe/*maybe* worth paroozing
OB/GYN - I would actually suggest reading, not bad
Sorry if the post is long, but I have yet to see a full length post on specific Step 2 resources.(I'm sure someone will find a post somewhere, though)
Good luck folks!