My guess is that the odds would be the same either way. Why not book into standard view for the full four days and just see what happens? If they don't upgrade you when you check in, you can offer to pay for one when you arrive. The only risk you run is that there will not be any savannah or pool rooms available, which would be unlikely I think given what I understand are the limited number of rooms that they have in the standard view category. Possible upside is that you will get a one or two category upgrade for free. Warning, though, if they give you comp upgrade from standard to pool view, a further upgrade to savannah view will cost you the difference between standard view and savannah view...not just the difference between pool view and savannah view.
Good luck.