Stephen, the San Rossore station is only a few blocks and a few minutes walk from the Field of Miracles with the Tower and other sites, as opposed to a major hike through the city and 20 to 30 minutes to Pisa Centrale. However, as I remember, when I got off the train at San Rossore (on an afternoon trip from Lucca) there was no staff, no signage toward the Tower etc., no businesses nearby. I was the only one getting off the train there, and there was almost no one around. Fortunately, there was a couple pushing a baby stroller, locals I figured, I asked them, and it took them a couple of minutes discussing between themselves to decide which street I should take toward the Tower. Bottom line, it's not exactly obvious, or very user-friendly. Also, I'm not sure if all the trains stop there in both directions, or if it easy or even possible to buy a ticket there. So, if you are going to be very short on time, you better do good research on this.