Our first aft cabin will be 9258 on Brilliance, but its not till April 2005, so can only say what I have been told, other than to say I have heard good things about them and the balconies are larger. Looking at the deck plans, 8168 is large but no side like the deck above 9256. The deck plans usually are pretty close to true size.
Three of us couples had 9260 9660 & 9658. We loved them all. In fact we are sailing on the Serenade and will have the same 3 cabins. I was in 9658 and we had an enormous amount of deck space. We had a round table with 2 chairs and 2 loungers and still had enough room for several people to be out there. We stored our luggage out there, which freed up some space in the cabin.
9258 is larger than 8168 for sure.
Just a word of warning !!!!!!!!!! People above you can see right down on your deck. BE CAREFUL what you do ou there.