Hi All, wanted to chip in a couple of notes on the sign up experience I just had with Dining Rewards. Apologies if some of this is redundant or listed elsewhere in this thread or forum, but thought it may assist.
On registrations: I found that I could not register online (at the cheaper 255 USD price), as when I clicked submit, the button greyed out but then did not submit the form. Frustrated, I called the 1800 number to register, and was given (without asking) the discounted price of $279 AUD - I thought the promotion for the cheaper price ended at end of December. If you're on the fence of joining, you may wish to call now and save $40!
On Availability of Free Nights using the e-certificate: The online chat / reservations team are able to confirm whether or not free nights are available before you sign up for dining rewards. This is great for those (like me) who are using an expensive night at an IC hotel to justify the cost of the program. The reservations agents claim that availability of free nights and regular award nights are different, though my searches after joining suggest they are the same (once registered, free nights can be booked online).
On time before your status upgrade: I was instantly flicked from Gold to Platinum on receiving my credit card receipt. However, the lady on the phone advised that I could take a copy of my registration confirmation email to receive discounts before my card arrived.
On duration of membership: I registered today, 5th of Jan, yet my IHG account says that my Dining Rewards expiry is Feb-2016. Whether this is at the start or end of Feb, I seem to be getting at least 27 days of free membership-upgrade and other benefits - so kudos to IHG for their generosity here.