I've been down this road before....a number of times. I've yo-yo'ed between 160 and nearly 200 probably 5 times since college.
Best method I have found is low weight, high rep weight training, combined with a diet you can tolerate. If you want to lose the most the fastest, it's Atkins, or some other low carb option. If you want to keep your special lady friend on the same diet as you, then South Beach or Weight Watchers is the best option....but you lose it slower than low carb.
I could lose 3-5 pounds a week on low carb for months. On Weight Watchers I have lost about 2 per week, but have been generally pretty happy and able to eat food in most situations (work dinners, road trips, family get togethers, etc.).
Booze is my weakness. I like the booze, so I had to switch to Mich Ultras and Vodka Fresca's.