Whenyou travel with small kids, you will need to bring more lugage. We brought our son's goat milk dry formula to Italy, diapers, linens for our rentals, dish soap, washer soap, tea towels, dish sponges, plastic glasses and dishes, microwave and storage containers, vinyl table cloth for picnics, beach towels.
If you are renting a car, you will need to bring a car seat, or rent one. Car seats are expensive in Europe and the rental means you will pay as for buying a new one.
We brought a collapsible and portable car seat for our son to Sicily. I purchased a Compass car seat, which he used for many years and into his tween age back home. To carry the seat I bought one of the first 4 wheels bags, where I could stuff lots of things. The bag was expandable. It seemed as a nice idea at the time. Finally, the bag being very big, it was not that easy to navigate even on 4 wheels. It was still possible, however I had lost a few pounds pushing it in hot Catania on our way from the ferry to the train and then to our hotel in Giardini Naxos. By the end of the trip one of the wheels broke, and the bag became unusable although in almost new state.
It was much easier with a booster seat on our next trip. Still I had to return one of them as it was too big and didn't fit in our suitcase.
We are usually renting a compact car, so we have to think and ensure our luggage will fit, and be out of sight if we want to visit a site. Really in this case less is more.
We migrated from 29 inch suitcases to a 28 inch and a rolling duffle of 30 inches. We reinforced it with metal gaskets so we could carry it as a backpack when needed. The advantage of a bag is you can easily reduce its volume by transferring clothes to a smaller bag and it takes the shape we need. It is an art.
For many years we traveled with suitcases with inline wheels and it was the easiest solution. We are going to Spain this year and will be using public transportation, so we need new suitcases. When I went to the stores, well, now 99% of luggage is 4 wheels. This is not a good solution for Europe. I believe the person who decided to convert all luggage to spinner sort has never traveled and just wants to maximize profits selling luggage.
I really believe it is a bad idea to have any luggage with protruding parts. It will break easily. It is a physics law. Then people are shown all sorts of tests on the suitcases. Funny, but none of them really test wheels, the real weakness. I don't see any advantage to have wheels in the air. On rough surfaces they won't roll. When you go up in the train or bus you have so many chances to damage a wheel or 2. Even lugging into a car, still protruding, so you can damage your car and the suitcase. I am not even talking of scratching yourself.
May be some airports have impeccable surfaces, but I am yet to see a street without a crack in the asphalt or pavement. People are tilting these suitcases, and damage the wheels, then you lose its purpose of gliding. I still have the image of my 4 wheels bag brand new but damaged with no possible repair. How about environment? This solution is very polluting as people just trow suitcase and buy new ones for each trip. There should be taxes to recycle these suitcases in the same way as for the tires and the manufacturer should take them back.
It is may be fashionable but not practical at all. I had a discussion recently about my insurance, and it is the same thing. People who sell insurance don't know anything about it, nor they own a car or a house, nor they ever have purchased an insurance or claimed any damage. Therefore, they couldn't answer any of my questions. They never traveled and live at their parents place. My conclusion is the companies are hiring students to cut the costs, and they provide very imaginative, but completely naive solutions.
I would like to have a chat with the engineer who designed these suitcases. They probably never walked 2 blocks with such suitcase, nor ever checked their luggage. The Romans knew big wheels are better than small. So, in 2000 years we are back to small wheels? Well this person should visit Pompeii to see for themselves.
2 wheeled luggage is not always solid neither, however, it is more common sense, and ours survived numerous trips to Italy, Spain, France, Holland to site a few, old streets and stairs. Now I am told to abandon common sense and buy 4 protruding flimsy wheels made in China. The worse part of it, some seem to enjoy it, but even worse we don't have choice anymore, as no sturdy 2 wheels bags are sold anymore.