What is the best way to do Cinque Terre in one day? I did the boat the last time I went from LaSpezia. Or can you do a combo boat and train or just book a tour?
I have tried twice (unsuccessfully) to do it all in one day. What we ended up doing and what I would recommend is to just pick 2-3 towns and explore them and walk between them and maybe take a boat or train back. Even in my younger years, I ran out of steam trying to do it all. I guess if you didn't do any hiking you could get to all of them in a boat or train, but we were trying to hike.
If your goal is simply to “leave a footprint” in each town then I recommend taking a scenic boat ride in one direction viewing each town from the water. Disembark at the last town then take the train back and get off in each of the five towns on the way back. Otherwise, as stated above, it’s tough to truly experience each town in one day.
It depends on what you mean by "do". What do you want to get out of the trip there? You don't mention hiking (one of the main attractions in the Cinque Terre). Do you just want to look around, perhaps have lunch somewhere? Then a boat ride so you can see them all from a boat, with perhaps a stop in one town to look around and have lunch. Or perhaps you could take a boat to one of the towns, walk to an adajacent town, have lunch, and then take the train back? Unless you have some checklist of the five towns and you must stop at all 5, there doesn't seem like a good reason to try to see all five in one day.
Anyway, whatever you decide, good luck with your trip. It's an exciting place to visit!