Here's something I can speak about with personal experience. I have been both a laborer and an intern the past two summers. The main difference between the two positions was scheduling and responsibility. As a laborer I had a set task to complete everyday, as opposed to the variety of jobs I could have been doing as an intern. As an intern, I was held to more of a management position, actings as a semi-assistant to the super.
I made almost double the money as an intern. But that was after I had the experience as a laborer, and in a completely different environment.
Both were valued experiences, but you definately get your hands dirtier as a laborer. And probably learn more in the process, even if it is in fewer areas.
This summer I was one of four interns, which was probably one too many. But this was golf construction, not maintenance.
Getting at what I belive is the heart of your question, I think that you can get more out of quality laborers because they will be there longer. Not to say that that all the laborers I've met are completely commited and enthusiastic to golf construction or maintenance. Not to say that interns don't work hard, but its definately more of a short term investment for someone who is passionate and willing to learn.