Cargo Capacity ???

I am seriously considering getting a late '90's or ealry 2000's H1 Wagon. My only holdup is cargo capacity and ride comfort. I have three very large dogs (2 St Bernards and a Newfoundland). The smallest is 135lbs. I drive from So Cal to Boise, ID at least three times a year. I currently do it in a Ford Excursion and we all fit and the ride is not to bad. Will my dogs fit in the back of a H1 for a 16 hour drive? Will I be comfortable driving 10 to 16 hours straight? Thanks for your advice.

The H1 will be crammed full compared to your Excursion with 3 dogs that size roaming around; the wheelwells area won't be very useable for them.  A Hummer H1 can be somewhat comfortable on a long ride when it is properly maintained and has good tight steering components, well-balanced tires and wheels, etc -- but not as comfortable as the Excursion.  If those are primary concerns for you, I think you are looking at the wrong vehicle; your Excursion is much better suited for long, on-road trips with 3 large dogs.