Living in the N.E., I've been able to attend all 3 of the largest Crossfire GTG's. Carlisle (basically a huge Mopar Car show) where everybody displays their cars, and mostly sit around (under a tent) and BS with other Crossfire owners. Not that there's anything wrong with that, because everybody always seem to have a great time since we all share a common love for the XF. But it doesn't include much actual "driving" unless you caravan to and from the event with other XF owners. Usually a 2 night affair.
Woodward Ave. which is simply unimaginable unless you've actually had the chance to experience it. Cruisin the Woody with a large # of Crossfires always attracts a lot of interest from the crowds, and it's amazing how you get to see practically every 4 wheel, 3 wheel and 2 wheel conveyance ever created. Again it's usually a 2 night gtg. but it actually gets started earlier in the week. Lots of time to hang with other XF owners.
The Dragon, probably the best, and the most fun GTG of all. Beautiful scenery, fantastic roads, great Lodge, lots of time in the evenings to party with fellow XF owners, again a two night gtg but you may enjoy staying longer. It's the best one to be at if you really want to put your car to the test. Nobody ever leaves the Dragon thinking the Crossfire isn't a "true" sports car.
If I lived out west, Arizona, Calif, Nevada, New Mexico, etc. In my opinion, Moparrbust's suggestion of attending Mopars at the strip, and a well planned cruise out to the Valley of Fire would be a fantastic GTG. Maybe even throwing in a more leisurely drive to Mt Charleston on the 2nd.day. Everybody staying at one central location should garner a group discount, and of course I'm sure everybody could find something to do as a group or by themselves in Sin City.
And of course, a simple cruise up the Pacific Coast Highway wouldn't be too shabby either.
The forum members in Florida have a real nice GTG at a Race track that seems to have adopted them (as a group) as an Opening Day feature in the Spring. They actually get some track time much to the delight of the crowds, and Forums member alike. Maybe this is another event that could be duplicated by some tracks out West.
What ever you guys do, it goes without saying the Crossfire makes it a blast just because it's so much fun to drive. But I've found that just getting the chance to meet all the really great XF forum members to be the real icing on the cake. Good Luck.