Anything at Kona Cafe ... the soon-to-be legendary zebra domes at Boma ... but, when in the parks or most anywhere else, carrot cake. I think they use the same recipe most dining spots, and it's as good as I've ever had.
Re the s'mores at 50's Prime Time - I can't imagine any normal human being finishing that particular dish. It fed four of us easily.
That photo of bananas foster sure looked good - but, being a purist (living right up the road from New Orleans and Brennan's, birthplace of bananas foster), I've never seen chocolate drizzled on 'em like that, nor with whipped cream. But, hey ... being a purist doesn't mean being a snob. Need to check this out one day.