If he is interested in BIG fish then he should target flatheads in the creek and they prefer live bait. Green sunfish are an excellent bait for flatheads but bluegill work as well. I doubt the bigger blues would go up a creek unless there is a big rain and the creek comes up. But flatheads will definetly. They prefer to be around structurs such as downed tree tops.
Fishing on the Missouri itself from a wingdam would get him into big fish as well. The bigger blues prefer the scour holes at the end of the wingdam.