Just to chime in.....Both breeds (Retriever and Rottie) are high energy and need to be occupied, so they're going to chew when they're bored.
Rotties are big chewers, so you need tough toys. The filled Kong mentioned was a good idea. It gives them both physical (jaws) and mental stimulation because they're trying to get that yummy stuff outta there and trying to figure out where it is, etc. When I worked at the Humane Society, we bought an enormous jug of generic peanut butter every month or so and filled all the dogs' Kongs. It kept them busy all day.
Crate training is also awesome! I had a Pit/American Bulldog with severe separation anxiety. He chewed/ate EVERYTHING. I bought a crate and it worked wonderfully. There's lots of internet resources and books available on how to do it properly.
Something else I always told people at the Humane Society is that WE'RE the ones with the bigger brains! That means that we know how to put things away, out of reach, etc. They're just doing what dogs do. So, put those shoes away, put books on higher shelves, etc.
Also, I found with my American BD X, he would get bored with the same toys, so I would give them to him in rotations, not all at once. And throw a new one in every chance you get!