Rome to Venice Day Trip?

It's almost 4 hours one way. Do you want to be in a train for 7 1/2-8 hours? you would have to leave very early and come back very late. I think you would enjoy it more if at the minimum you made it an overnight trip which allows you to enjoy Venice in the evening and early morning when there are less tourist.

Doable, yeah, would you enjoy it....meh.

It looks like you could catch a train as early as between 5 and 6 in the morning, get there about 10:00 a little before, then catch a train back about 8:45 PM, getting back to Rome about midnight. A little over ten hours on ground, maybe cost would be less than 100 euro if you book ahead.

My preference would be to do an overnight, then you get to enjoy the best time in Venice, the evening, and you can relax rather than rush.

The transportation infrastructure exists to go to/from in a single day.

Enjoyable? Whole different question.

Would you go to Spokane as a day trip? About the same distance/travel time.

Yes, you could leave Rome early and get to Venice just in time to meet all the OTHER throngs of daytrippers that clog the city's alleys and squares. If you want to see Venice (and you most definitely should) you need to at least spend 1 night there.

I didn't want to be a naysayer but I just think it is pretty far
away. Is worthwhile to consider doin this?

Yep, pretty far away. Nope, not a worthwhile trip in my book.

Thanks for your info. Pretty much confirms what I thought. I'll advise them to book an overnight for Venice. Are there some modestly priced accommodations with good access to train station?

Nothing, in my experience, is modestly priced in Venice, although it’s all relative. I recommend looking at Booking.com for the particular travel dates.

I stayed in Ai Mori D’Oriente Hotel which was in a quiet location, but easy to get to the sights and the rail station was a 20 minute walk.

The main sights aren’t close to the rail station, which is at the northern end of the islands.

Just have them look at Booking.com and put in their parameters for a room. It will be expensive to go there for one night or even a day trip (which is ridiculous) unless they get train tickets far in advance.

Venice lodging is expensive but it is Venice. I'm guessing that one night will not bust your travel budget. When we went we found a room through AIRBNB. Go, see, enjoy!