Hi Angie-
I've done both so I hope I can help.
The Zone is a diet program. BFL is nutrition/exercise combined. If you are sedentary, the Zone can be fairly effective (to a point) for weight loss. If you do any exercise, the Zone is just not enough food. You'll lose muscle as well as fat, and I know this from personal experience.
But you're smart enough to know that you and dh need to do exercise too!
Doing the Zone is a mathematical pain in the butt. You have to figure out your "blocks" allowed for the day and plan all food from there. Lots of weighing and measuring involved for everything.
On BFL, you can use your palm (protein) and fist(carbs) to measure.
On the Zone, there is no free meal, free day, or anything.
On BFL, you get a full day each week to eat what you want.
Please don't worry about "bulking". You will lose fat doing BFL and yes, your muscles will get stronger. But 99% of the population cannot get "muscle bulk" without serious steroids. Especially women.
You don't need supplements. The book (try half.com for a good price) talks a lot about shakes, but that's because the author used to co-own a company that makes the brand he recommends. You can certainly use shakes for meals for a meal here and there, but real food is better.
HTH
Laura