Hi Danielle,
I recommend a good Hunden Flaucken. Try Schecker, they have a great selection of anything you could want for big kids. It is the best. Flaucken is all natural and has dried veggies,pasta,oatmeal(great for sensitive tummies),cranberry,blueberry and so on. It looks cereal and comes in a bag. Mix with hot water and then add meat of choice or dry food. My kids love fish and the oil is great for the fur. A little pumpkin cures any nausia and plain yogart once a week is a great treat and cleans away any bacteria picked up from being out and about the town. For long road trips or the dreaded plane trip I HIGHLY recommend CATNIP. Sounds crazy, I know. Any good European vet will tell you to put catnip in a piece of cheese. It is a natural and harmless sedative for dogs (and humans!) unlike tranquilizers. The Flauken is inexpensive and when we came to the states we still feed the same way, only I have to make my own Flaucken because they don't sell it here. This is a pain. If you are a military family, I'm sorry to say the PX doesn't sell a worthy food. Especially for Giant Breed. Our breeder has been showing and breeding for 27 years and we took her advise on feeding to heart. It wasn't the generations of champs in our boys bloodlines, it was how long they lived that mattered to me. When I knew that what I fed my kids could be the line between 8yrs and 14yrs of life, I was all ears.
Best of luck to you and if I can help in any way...glad to help