If you've got an FF guarantee, that means at a minimum you'll have the Emerald Deck with a fully obstructed view. The only other obstructed view above FF is a partially obstructed view -- Cat E, also on the Emerald Deck. On the Grand, the Emerald Deck is the only deck with obstructed views. If you get upgraded further, an unobstructed outside cabin could actually send you down 3 decks to Plaza. Other than that, your upgrades would be all uphill from the Emerald Deck. I pasted below, a response from an old post I wrote with my experience on obstructed view cabins.
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The obstructed view is as a result of something hanging in front of your window - usually a lifeboat. In the case of E407, I believe it is a partially obstructed view. There doesn't appear to be a lifeboat hanging directly in front of that window, which means the partial obstruction is likely from some of the lifeboat related stuff such as davits, platforms, catwalks, etc.
If you're interest in the outside cabin is for the view, then you should move because the panorama will be significantly restricted both left & right as well as down (you look down at the promenade deck). If you're just interested in the sunlight and knowing what the weather is, then keep it for the money you're saving.
I often book the obstructed view cabins to save on the fare, since I just like to have the light coming in. If I want to look around I usually go outside anyway, unless I've booked a balcony cabin.
Have fun! We've enjoyed the Grand every time.
