Going to be doing a long day trip from Florence and planning on one of these. Thoughts on one versus the other?
6 hours or so riding trains, plus 6 hours there pretty much fills you day. You will be there when the day-trippers are packing the place. You may want to consider staying overnight, or saving CT for another trip when you can spend 2-3 nights there and enjoy the area.
Train or car? What month?
Don't get me wrong, the CT is beautiful. I have only visited once but was disappointed because it was SO crowded and expensive. I would choose Lerici, especially if you are visiting when the weather is warm.
Note that Lerici is not served by train. You can switch to a bus at Sarzana (or La Spezia). Also note that a Google search of Lerici will turn up a mix of photos that include Porto Venere and some other towns, so that can be confusing. Porto Venere is accessible by boat from Lerici or the same local bus system.
https://www.atcesercizio.it/index.php/en/
We went to Vernazza in March and there was practically no one there. It was great!