The Town Car Ultimate is sweet. Snagged one of those at SEA and was very impressed - heated leather seats, sunroof, back-up radar sensors. The Town Car Executive is more spartan, but more prevalent. Did see an Ultimate at GSO, however.
Only driven in the Caddy from AVIS, which is a "stripper" model, but the Northstar V8 is more powerful then the V8 in the Town Car.