We just bought the Honda Odyssey with all the frills, and we LOVE it.
Big 6 cylinder, that automatically goes down to 3 (economy) when you're maintaining a steady speed.
Also, my brother just bought the Toyota Highlander Hybrid, (SUV) and likes it very much. But it's nowhere near as comfortable as my minivan.
I wish Honda or Toyota, or any of the car manufacturers, for that matter, would produce a hybrid minivan in the US. There is one on the road in Japan already. It is a Toyota, but a little smaller than the Siena.