I'm on my second Odyssey and will soon be upgrading to my third. Three of my friends have Siennas and love them as well. If you're trying to decide between the two, consider this. If you are going for top of the line, get the Sienna Limited. It has a few more feature than the Odyssey Touring, like available AWD and power folding seats. If you are going for middle of the road, get the Odyssey EX since both sliding doors are power (big feature) as opposed to the Sienna where only the passenger slider is power. If you're going for the base model, go with the Odyssey as well. Middle row aptains chairs and side curtain airbags are standard, not so on the Sienna. Also, the variable cylinder feature on the Odyssey is a gas saver for highway drivers. I think it's available on EX and avve models. Hope that helps. I've put more research into this subject than I care to think about! I love the website Edmunds.com since you can compare features side by side. Good luck!