Many of my favorite summer memories are from road trips with my wiener dogs. We have done so many that I have the art of packing thier gear down to an art. Obviously, every dog, travel group, travel destination, and travel journey is different, and will likely come with a few extra packing requirements. But all in all, these above are the main things I do not leave home without!
Certain items on the list are obvious, such as dog food, leach and waste bags. Some items are extremely useful, yet surprisingly easy to overlook — such as a towel (a must!) and vaccination papers (crossing borders, to participate in certain activities/events, in case of emergencies).
Other items I have learned to pack from years of experience, most notably, are dried or canned pumpkin (bring a can opener if you bring canned!), which is amazing for stabilizing doggie digestion. And some things seem repetitive — such as the 3 types of water delivery methods I’ve listed. Sure, you could just bring one bowl. I did for several years. But, from experience, I have learned that: a normal bowl can be knocked over in the car or crate (hence the usefulness of a crate-attachable bowl/bucket), that a water-bottle style water dispenser is very easy and useful for bringing on hikes and in the passenger area of a car, and lastly, the food & water station is perfect for leaving in the room you are staying in (nothing is more annoying than forgetting to bring the bowl in from the car, or forgetting to bring the bowl into the car, etc). I pack light, but with convenience and safety in mind.
I think it is better to bring multiple water-delivery items, and save space with toys. Bringing one favorite fetch/treat-stuffable/quiet toy is ideal. If your dog is nervous at the new indoor space (hotel, home, room, etc) you can stuff the toy with treats and let him or her relax by foraging for treats — instead of stressing out, or worse, barking! The toy needs to be quiet for the sake of hotel room neighbors, or whomever you are staying with. If the same toy can be used for fetching, you can also take it along outdoors.