We’re currently in Florence and we’re thinking of a day trip by train. Pisa seems appealing because it seems so accessible. Livorno, appealing because of the coast. Thoughts in favor or opposition to either? TIA.
Pisa is an easy direct train ride from Florence’s (Firenze) SM Novella station (1h) and makes a great day trip. The same with Livorno that takes an extra 15m.
For Pisa, which is a great town, there are six self-guided walks on gpsmycity.com.
If you've never visited either, Pisa is more interesting as a city to visit.
But if you want somewhere more different from Florence, and definitely less touristy, Livorno is worth a day trip.
https://slowtravelitalyspain.blogspot.com/2021/06/costa-degli-etruschi-may-2021-livorno.html?m=1
Bear in mind that Terrazza Mascagni where there's the splendid sea view is about 4 kilometres walk from the station, although you go through the centre to get there
I would pick Lucca over your first two ideas.
One hour and 40 minutes or so by train, and very worthwhile for a day trip!
Not as crowded as Pisa and lots to see, do, and eat.
Another vote for Lucca. It is a charming walled city and an easy walk into to mainhistoric district from the train station.
Definitely do Pisa and Lucca together. We went to Pisa ( from Florence) to take the picture holding the leaning tower up and then took a train to Lucca. It is a charming town. You could ride bikes on the top of the wall or walk on top of the wall.