Clicked this since we have an upoming cruise in a suite on Ovation. Your question is interesting but I think it is a little too vague. Did you mean a Junior Suite Guarantee? Other category?
Selecting that Guarentee could be a win since it probably will have a lower cost compared to selecting a suite outright. It seems that most of the suites, except the Star Class level, are near midship. It doesn’t seem much of a gamble if you are willing to give up that control and save what is likely a couple hundred dollars. I heard the discount is about $300 so someone could argue if the savings is not that significant, why not just pick the room.