If you had wanted to or planned to eat at Tiffins, the Dining Package can be a good deal depending on what you order plus you get a pass to the show. Some that have done both have stated the Dining view is somewhat better than the FP+ view. I have done the FP+ and each view is different due to the positioning of the floats. I'm not sure there is a huge advantage to one or the other, it depends on if you would like to dine at Tiffins.
NOW, depending on when you are going (looks like later) I would think about Tiffins because that opens a FP+ for you that can be used elsewhere since Pandora will now be a hot FP+ to get. If you get one of those, by dining, you will still have two left for other things and maybe even roll a 4th. Pandora will bring more crowds to AK, so FP+ may become more important there. If you had for ROL you would tie up your last one all day, unable to roll a 4th.