If you're into researching what you're feeding your dogs, I'd recommend checking out this site:
http://www.naturapet.com/tools/comparison.asp

I've been feeding my 8 year old Weimaraner California Natural (dry, chicken & rice) and Merrick (canned) food for about 2 years now. Prior to that I'd tried everything (ScienceDiet, Eukanuba, BillJac, Purina, etc.). Yukon looks, feels, and acts younger now that he did when he was 3-4 years old. California Natural is a little expensive by volume ($22-$25 per 20lb bag). However, I used to feed Yukon 8 cups of dry food a day. The foods he used to eat were full of filler that just ends up in your yard. Now he only needs 2 cups of dry food a day, about4 tablespoons of canned food a day for extra flavor, and a mix of green beans and carrots at dinner with his dry/canned food. We've also started adding fish oil capsules to his meals which has made a big difference in his skin and coat.

We got hooked up with a young vet who is really into animal nutrition and she turned us onto these dietary changes. Ultimately, Yukon is happier, healthier, and will likely be tromping through the field with me for a few extra years because of a better diet.

Sorry for being long-winded, just tossing in my 2 cents...