hi S.
while the minivan image wasn't quite as cool, i am a practical person so we went for the sienna. i'd heard vans were much easier to load strollers and get carseats into. also it seemed like every SUV i got into had that rollover warning on the sun visor and that freaked me out.
it's a close call between the odyssey and the sienna. i think they're running neck and neck with the options these days. (we bought a 2004.) here were a few options that were available on our sienna but not on our friends' odyssey at the time:
-the windows in the odyssey's doors didn't go down and i really like that feature.
-the 3rd row seat (odyssey) did not have a split so either you had to put down the whole thing or leave it up.
-the door tracks on the sienna aren't as obvious
-the rear door on the sienna is automatic. this is a lifesaver when you've got a baby on one arm. just give a little tug on the handle and down it goes. or you can push the button on your keychain.
if you're an audiophile, you should know that the sound system is not great in the 2nd and 3rd rows in either but seemed slightly better in the sienna.
our friends got the factory DVD option which comes in the ceiling. it has a crummy screen and is another visual obstacle (in addition to the headrests) when you're trying to look out the rear view mirror.
in either van, if you're looking for a DVD player, i'd suggest getting it put in after-the-fact. they charge too much for this option and don't give you the best stuff. plus you can have it put in the back of your headrests.
our friends did get the navigation package on theirs. it is very nice and sometimes i do wish we had one as we recently moved and i'm getting lost a lot in our new town. (on the plus side, i'm getting to know where all the streets are.) we looked at this package on the sienna (XLE i think?) but it was $8000 more. it included a sun/moon roof and a rear camera for backing up plus the factory DVD. too much for those options in our opinion.
one thing i do find annoying in ours is that when you lay down the seats, the armrests don't go any lower so if you wanted to put your arms on the armrest, you'd have them pointing at the ceiling. probably the same in the odyssey.
another thing i wish mine did was to have the 2nd row seats go into the floor. there is a minivan out there that does this and it would be really handy when we want to move big things. you can take out the seats but they are really have and you have to plan ahead. no good for big impulse purchases.
oh and the sienna drives just like a camry because it's built on the same frame. we had a camry before too.
bottom line is that you can't go wrong with either minivan so it will come down to options & $. i think they both retain their value fairly well so are good for resale when you're ready to get a 'cool' car.
as to safety, again i think they're pretty close but the odyssey had slightly higher ratings a few years go.
here are your links:
http://www.toyota.com/sienna/models.html
http://automobiles.honda.com/images/banners/2007/odyssey/...
happy shopping :)