We recently did a trip from Georgia to Anchorage and back. The road portion of the trip (9500 miles)was fine with our 2 dogs (redbone and a yorkie- both mature). The dogs always have been great travelers and seem comfortable when we were away from the rig site seeing at various stops. We enjoy their company and- except for seeing furry type animals along the roadway -they were very quiet and seemed happy. The weather was cool all the way so we were able to safely leave them inside the TC when we were away from the rig.
We made sure we stopped while riding the roads about every 2 hours for a good walk with both dogs. They enjoyed all the new smells and romped around at each stop.
We did bring them back on the Ferry from Whittier to Bellingham. They had to remain in the rig for extended periods which was very hard on them (and us thinking about what they were going through) over a 4.5 day period. We will not take the dogs on the ferry again as it was too stressful for them.
Other than that we take them everywhere we travel = and all of us have a great time.