Train from Venice to Rome, buy tickets in advance?

Its a 92 EUR ticket (2nd class) if you just go to the station and buy a ticket for the next train. Just checking a random date in late July, nonrefundable Super Economy tickets are costing 44.90 EUR. Prices will only go up from here. Is 47 EUR per ticket something that makes you think? If you know you have to travel from Venice to Rome on a certain day, why think about for the next 10 weeks? Pick a convenient time at a price you like and commit. Then cross it off the to-do list.

Do you wait until you get to the airport and buy tickets because you want to be flexible? Probably not.

True, using loco2 I am looking at about 125 USD for three of us, not bad. Just need to figure out which time to pick and go from there, thanks.

I buy mine ahead of time. It's cheaper and I can work my itinerary around my travel times.

It’s really a no-brainer decision. You already know the date you have to travel...so why wait and spend more. Buy your ticket for s convenient time and be done with it.

I'd pick a late morning departure.
1) Early departures are what business people take. They are not paying out of their own pocket and want to get to where they are going, take care of business, then get a train home in time for dinner. Prices are higher.
2) You might want to get up early and see Venice as it wakes up. No crowds.
3) You might want to have a leisurely breakfast at a civilized hour, before checking out of your lodgings.
4) It may take up to 45 minutes to get to Santa Lucia station from your lodgings on the vaporetto.
5) It takes 3 hours and 53 minutes to get to Rome. You probably can't get into your new lodgings before 3 pm, so whats the point of getting there sooner? Pack a picnic lunch and relax on the train.

There is an 11AM, 1PM and 2PM option for departure, arriving at 2:41, 4:33 and 5:33 respectively. Trying to decide between the 11AM and 1PM at the moment. We are doing two full days in Venice so this departure day will add some additional time to those two full days. I'm not sure at the moment if we will be ready to just move on and go with the 11AM or will want to hang out a little longer and prefer the 1PM, in any case I'm splitting hairs being only 2 hours difference either way.

Prices are all the same, looking at 107 euro for all three of us, not bad.

The other factor is when your Venice lodging requires you to check out. If the 1 pm suits you, buy it. You just saved your selves 169 EUR.

If you have a definite date, then it makes sense to get tickets well ahead. The only time that has risk is if you are flying into a city, then trying to catch a train elsewhere...in that case you are risking being delayed, then having to buy a full price ticket anyway and losing your non-refundable ticket.

I like to arrange train travel between checkout time/ checkin time. Pick up food at the station and have a train picnic lunch.