Don-
Regarding Emily, the longest mileage day was 375 miles. I know, you guys easily do twice that. An average day was 225-250 miles-that could easily be a whole day of riding/stopping/looking on 2 lane curvy roads. We would stop 15-30 minutes every 1.5 to 2 hours on long stretches. She never fell a sleep. A pool at night sure helped (had a pool a bout 1/2 the trip). We do not have a GPS so letting her help with the maps, routes, signs, and having her involved helped keep her interest. We always left by 7:00 am and stopped for the day by 3-6 pm.. This worked for her and ourself's.
We were leaving our Bar Harbor motel to catch the ferry and 2 college age girls were leaving and one yelled out the car window- "you're the coolest family ever". Emily doesn't think so and those who have met me know I'm not cool.
Thanks Pollux and WFP for the nice words.