Join Date: Dec 2013
Location: Boston, MA, USA
Programs: UA 1K, DL Gold, IHG Diamond AMB, MR Gold, HH Diamond, Hyatt Globalist, National EE
Posts: 1,087
Yes, prices will fluctuate significantly.
Book the best flexible rate, or the AAA rate which is just as flexible, and you can always call IHG if you see the rates go down and they will adjust accordingly.
Note that if the hotel has already pre-upgraded you based on AMB or RA status, and then you have the rate adjusted through IHG, the hotel will have to re-do the upgrade because your reservation will have been reset to the original room type.