I have worn diapers on almost all vacations I was ever on.
There have been 3 phases of this. The first phase lasted from when I was first born until I was 8. I wet the bed and had to wear diapers every night, so of course, when on vacations I had to also wear diapers to bed. If the drive was going to be long, my brothers and sisters and I usually wore diapers just in case until we were six or out of night time diapers. It was easier than having to stop when we could not hold it that long and often had accidents. After we were six, we usually had our choice wether or not we wore diapers if we were out of them at night.
The second phase for me was when I was 8 - 12. I did not have to wear diapers on vacation unless I wanted to, except for when I went on a long plane flight when I was 10. Other than that time, I usually did not wear a diaper while on vacation.
When I was 12, I started wetting at night so I was back in diapers at night and I no longer had my choice on long trips. If I had to wear a diaper in the car, I usually also wore a diaper when we got to the destination because no one could tell I was wearing a diaper under the jeans I usually wore. If I was wearing a dress (seldom), I usually took the diaper off when I got there and slipped my panties back on. After I started having daytime accidents when I was 16, I always wore diapers. I can't even remember the last time I wore panties.