Of the Silvestri scores I've heard, none of them give me a whole lot of confidence in his ability to write this sort of score. The guy is talented, no doubt - I was overjoyed when the Intrada released their Back to the Future complete soundtrack a month or two ago, for example. But I haven't heard anything of his that really tells me that he's 100% up for the job. Goldsmith and Williams, on the other hand, had/have already written numerous works that showcase just the kind of approach that the attraction needs.
How 'bout Soarin' Over America? I like that idea, because it can begin and end in California and showcase some of the places they do now, but add other beautiful places of our country (Grand Canyon, Manhatten, Yellowstone, etc...). it would be BRAND new, longer than the original, and would still themetically make sense without having to get a souvinere from the Taj Majal What do u think?