Your thoughts on a Cinque Terre day trip

Makes perfect sense to me! You could also park at La Spezia.
Montemarcello park is also nice.

Go for it.

I'd ride the train in from LaSpezia too.

Driving in and out of Monterosso consumes a lot of time. There's a modern parking facility under the La Spezia Centrale train station. https://cinqueterreinsider.com/2019/03/23/parking-a-great-alternative-for-those-driving-to-cinque-terre/
It will show if you enter La Spezia Parking in Google Maps, as well other facilities nearby.

Chris,

A day trip from Lucca to the Cinque Terre is certainly possible. I'd suggest getting an early start and staying late, and travel by train would probably be easiest. I checked briefly and the shortest trip from Lucca to Riomaggiore appears to be 1H:32M, with two changes. If starting in Monterosso, the shortest trip appears to be 1H:54M with one change. You can start at one end of the CT and return from the opposite end.

I'm not sure whether the Sentiero Azzurro would fit your description of "nice, not crazy strenuous hiking". The only two sections open are the Monterosso - Vernazza and Vernazza - Corniglia segments. If starting from Monterosso, the first uphill section is quite steep, but once you get up to the trail, it's an easier walk (albeit narrow in some spots). I prefer to do that part in the "uphill" direction, as going down steep hills is harder on my knees. The Vernazza - Corniglia segment might be a good one to consider. Note that a Park Pass may be required to hike those trails - https://www.parconazionale5terre.it/page.php?id=157 .

Note that the status of the trails can change on short notice, due to adverse weather or whatever. Unfortunately at the present time it appears that all trails are closed - https://www.parconazionale5terre.it/Esentieri-outdoor.php . You'll have to verify that at the time of your trip.

Thanks folks.
So park in Viareggio vs La Spezia? I was just thinking it'd be easier and less hassle to train up from Viareggio vs drive.

We went there late October. We parked across from the Navy base because the train station parking looked sketchy (lots of broken glass on the ground).

When we got into Cinque Terra, however, we found we could have easily driven and parked in any of the towns (small parking lots at end of towns). I don't know if it was just because it was late October or if the parking/traffic hassles end with summer?

How far is your lodging from Lucca train station? Might be faster to train from there to Monterosso. Rather then Viareggio.

How far is your lodging from Lucca train station? Might be faster to train from there to Monterosso. Rather then Viareggio.

25-30 minutes

With you being equidistant for both locations, Viareggio will be faster, it’s a direct non stop train. No changes involved.

I would drive to Levanto instead of La Spezia.

If you are staying west of Lucca it should be an hour or so.

There is a bunch of traffic getting into la Spezia in the morning from the freeway. Although Levanto is on the opposite side of the Cinque Terre, you'll get there just as fast, and then you only need a few minutes to Monterosso or Vernazza by train.

And if it happens that the parking at the station in Levanto is full, it's just an additional 20 min drive from Levanto to the parking lot at the Fegina beach in Monterosso.

Viareggio is an option, but in my days the parking at the station wasn't too plentiful. I don't know what the parking situation is at the station nowadays. Viareggio gets busy.

The Cinque Terre is picture-postcard “I wouldn’t believe it was real if I wasn’t standing here” beautiful! I stayed in Manarola once and the view from the vineyard side looking back at the town with the sea in the foreground is amazing! There’s a parking lot at the top of the town; walk down the very steep hill a bit to access the trail thru the vineyard, or walk up the unusual stairway hewn into the mountain that is part of a road!
Monterosso al Mare is more sprawling with a great beach and a nice restaurant jutting over the beach. Bathrooms at that train station were squatty potties last time I was there!
Have fun!