The trick to using large landscaping boulders in your backyard or front yard is the strategic placing of them. If you just lay out a couple of rocks and don't think about where they look best, they can even look quite odd. They need to look like part of the landscape and they need to look like they belong.
One tip to make this work is to not lay the rock on the top of the ground but to dig a small hole and bury one fifth or one sixth of the rock. You can then put various ground cover around the rock and it will look like it naturally belongs. Making everything look natural together and not forced is the key to doing something like this.
Some rocks are so big and heavy that you will have to have a professional place the rock for you. Landscaping rocks can be any size, shape or color but you need to use ones that fit in with the environment. For instance, the boulders you would find in desert climates are different from the ones you might find in the northern parts of the U.S.