I did quite a bit of research and got quite a bit of help from both here, and the tortoise trust regarding diet and supplements.
I use Zoomeds Forest Tortoise Diet and their Grassland Tortoise Diet as far a commercial food goes. I also use collard, mustard, dandelion, and turnip greens both fresh and sundried. I grow plenty of grasses and a variety of weeds and feed both green and dried. Naturally dried grasses and weeds have a much lower protein content than fresh green versions of the same plant.
I also use sweet potato, endive, prickly pears, and oputia cactus. I have found that the Glendale spineless species is the easiest to work with... Obviously... And the fruit is very tasty!! Cactus margaritas and tortoise gazing is a great way to spend a warm afternoon 
I rotate many of the items, and also switch between completely diced up... mashed up meals to I hope that little beak is ready to work for it's dinner tonight.
No matter what is on the menu I always include semi dry Burmuda grass, and collard greens. I have stopped using multi-vitamin supplements for my torts and chucks, but still offer it once a week or so to the iguanas. I use calcium with D3 for the non-shelled group, and Tums for the tortoise... Vic told me to try this, and seemed to swear by it...
Of course, I am really a beginner with tortoises, but have kept Rock Iguanas, and Chuckwallas for over 20 years. Through experimentation, trial and error, and all the input from other herpers... I can honestly say that my scaled family has never been happier or looked healthier.
Just my 2 cents on diet,
-Kory