We have a 2002 Odyssey with a 151K and like everyone says the trans is the biggest issue. Ours went with 107K! Got Honda to split the cost with me.
The other thing to watch is motor mounts, and the electic doors. Also, make sure timing belt has been done, plugs replaced ($$$), and some of the vans need to have the valves adjusted.
Otherwise the van is great espeically for long trips. MPG's are weak but then again you are looking at a 10 year old mini-van.