I've done P1 about 5 or 6 times. I did it the first time to start SBD, did it after each time I did a planned time off of the plan (2 times in Europe, once in Canada), and a couple other times when I realized some sugar had gotten into my diet and I was craving. I find that one week is enough...and often only do M-F.
I hear you chickies about variety. I really need interesting food to eat or I get frustrated and feel deprived. I often save P1 recipes that I love, like the Taco Bake to make only during P1, so it feels like a treat. I love Cooking Light magazine...I am able to convert about 2/3 of their recipes very easily to SBD-safe dishes. Every month I have a new assortment of recipes to pick from...it's a lot of fun!