Are ALL pot roasts dry and tasteless?

I have made beef roast several times, in several diferent ways. What could I be doing wrong? They are always tasteless and dry. I tried searing the outside and cooking the inside in a crock pot for 4 hours, in a mixture of coke (which I was told was a tenderizer) and beef broth - it was the worst yet. It was extremely dry and had no flavor. I have tried cooking in the oven, but that is dry also. My best bet is cooking all day (8 hours) in a crock pot - it is more tender, but still lacks flavor. I put in kosher salt, pepper, potatoes, onions, and carrots with various types of seasonings. Maybe I am buying the wrong kind of roast? I usually buy Beef Chuck Roast - English. it is a leaner cut - maybe that is my first problem. Any ideas would be greatly appreciated!