I'm trying to book train tickets from La Spezia to Venice. Does anyone know if both of these are in Venice?

S Lucia is the "downtown" station, in the heart of Venice. Walk out the front doors of the station and stare at the Grand Canal. Quite a sight. That's the station you want.

Mestre is on the mainland & San Lucia is in Venice.
Hope this helps.

Bailey:

We never got to La Zucca last year, but we stopped in and it looked like a great restaurant - busy... Gives me a reason to go back next month.

Dave

Most likely you want Santa Lucia.

Not just "most likely" -- most definitely! On my first trip to Venice, I was getting ready to get out at Venezia Mestre, when three Italian gentlemen started gesticulating wildly to make it clear to me that this is NOT where I want to get off. "Santa Lucia, Santa Lucia," they kept saying.
It was obvious to them that as a blonde North American I wanted to see Venice and not its industrial and dormitory suburb.

Thanks all. That clarifies it. It's amazing how simple little things like this can stump you.

I used "most likely" because there could possibly be a reason a person would want to go to Mestre, after all.

And although it is not the case in this poster's case, if you are leaving Venice and want to book a Eurostar that only leaves from Mestre that is perfectly OK since local trains run between S Lucia and Mestre about every 10 minutes.

Yes as per Suki there are some trains from Rome, florence and Bologna and Trieste that only stop in Venice-Mestre, saving time on not having to limp into Venice S Lucia deadend station. On these services you must get off at Mestre and take the constant shuttle trains to S Lucia across the lagoon via the causeway - ditto for leaving Venice - if all trains from S Lucia are booked up ask for a train from Mestre.