Smaller states are usually also shrewd enough to keep their senators in office for really long periods of time so that they have a lot of seniority. Robert Byrd, Ted Stevens, Patrick Leahy, Orrin Hatch, Daniel Inouye, Thad Cochran...
It's weird though, because to me, it doesn't seem like Hatch does all that much with his seniority. Same with Cochran. I know the others either lead on issues or are kings of pork, but Hatch doesn't seem to have brought much to Utah or brought any issues to the forefront.