Depends on how long you are going for and if you are driving / flying. If you are flying and are limited in space I'd say Amazon prime or another delivery service. If you are not limited if just bring my own, but I normally drive.
We have done all of that. If we were flying then we'd just Amazon Prime it to our hotel. If we had a vehicle then it depending on what our time was worth to us. Amazon was often easier unless we were planning on going to Walmart anyways.
I always have space for enough diapers in my car. I get a luggage cart to take my stuff to my room wherever I go anyway...throwing the diapers onto the cart isn't a big deal.
We put half in one of our free 'personal items' and the remainder in a suitcase. Prime Pantry (where we ordered breakfast food from) didn't have everything I needed (swim diapers, overnights and preferred brand of diapers) so we chose to pack them.