C1 and D1 were "sub groups" developed by Radisson a year or two ago for those cabins most affected by the vibration. I have never actually seen a fare for those cabins; they always seem to show as "sold out." Those C1 and D1 cabins are the cabins that will become Cat F next year...if I recall correctly. Now that Ngaire has returned, she can post the complete truth.
As for cabin location, I don't think there is a cabin better than 627.
