Cinque Terre Itinerary

Where are you actually staying?

Do get ahold of a ferry schedule as that may be enjoyable. There is not a lot of sight seeing to be done in these tiny villages--it is really all about the views.

Here are all of the trails: http://www.parconazionale5terre.it/Esentieri-outdoor.php

Staying in La Spezia.

We are travelling in Mid-March and the ferry isn't open yet according to the Cinque Terre website.

Oh yeah, gotcha.
I'd plan on playing it by ear on arrival day--I don't know sunset time, but if you are delayed it is unlikely you are going to get much of a hike in on that day. But, you are so close to a really lovely area--use the car to drive over to Tellaro. It is Montemarcello park and there are some coastal hikes, great seafood. Just an alternative in case its' all too much bother for too little time.
Then the next day plan a spectacular day of CT hiking and a long lunch.

You might consider staying in Levanto instead if you need a car-friendly town. I've stayed there a few times (without a car). It's only one train stop north of Monterosso. I've not been to La Spezia but I understand it isn't quite as nice as Levanto. I guess with such a short stay it may not really matter where you stay.

You could even hike back from Levanto to Monterosso if you stayed in Levanto. It's not as nice of a hike as the other main trails but it's not bad, and you do get a breathtaking view back on all five Cinque Terre villages from just above Monterosso at the end.

The hike between Vernazza and Corniglia via Volastra is probably the most scenic hike I've ever done in the Cinque Terre - the views down are breathtaking. But keep in mind that it's a very steep climb up, up, up hundreds of steps! You can do it if you aren't in great shape - it's not a scary hike, but give yourself a lot of time and take it easy if you aren't that physically active. (I've not done it in the rain - not sure what weather will be like in March.) There's also a bus I believe from Manarola up to Volastra, but of course that eliminates half the fun and views. For what it's worth, no hiking pass is required for the hike between Manarola, Volastra, and Corniglia or the hike between Levanto and Monterosso.

Andrew, we already have our reservation in La Spezia and will be ditching the car when we arrive.

You may want to reconsider the amount of hiking and the time required; the trails are the opposite of flat land, and often narrow and rocky. Visitors are often disappointed at the exertion required. The Manarola to Volastra section is very steep even though it's described as easy. In March you may encounter wet weather and/or wet trails. Also, there is no ferry in mid-March.