The Sienna is an excellent family vehicle if interior space and overall capability are your priorities. It is comfortable for long family drives and you NEVER run out of space in this car.
Plenty of space for luggage, camping equipment, and anything else you want to haul. Also, decent towing capacity (3500 lb - we used ours to tow am 18ft boat), and usable roof rack (150lb capacity) which we used to carry two tandem kayaks.
The reliability was perfect - absolutely zero problems in 75,000 miles.