I Find These Trains So Confusing

I did a similar search given your information on Trenitalia, and got similar info, but a higher total price for 4 people (was yours per person or for the group of four).

Some comments:
Geneve is French for Geneva, Switzerland, and as that is the only option, I assume that is the main station, not the airport.

A change in Milan is correct, maybe a change elsewhere as well

You mention Venezia Mestre, but if you are staying in Venice proper you want Venezia Santa Lucia (Venezia SL) though the cost difference is almost nothing.

Rome2Rio.com shows an option from Geneva to Venice with a change of trains in Bologna, about six hours, on the Swiss railway. I found Trenitalia fares beginning at €49 per person.

Note that this info is all within minutes of each other's posts but shows a variety of routes and prices.

So, I just went ahead and booked the Italiarail trip from Geneve to Milano to Venezia Mestre(it didn't give me an option for the Venice proper) for $193 total for the 4 of us.
Hopefully my subsequent trips, Venice to Florence to CT TO Sorrento to Naples to Rome will be cheaper total? I guess I didn't get those cheap tickets I hear about everywhere? You snooze, you lose! :)

Please excuse me for adding my 2 cents, but I couldn't resist. So here goes: $193 for 4 people seems like a pretty good price for that distance considering that the regular base fare for one person travelling from Venice to Desenzano (1.5 hours, about halfway between Venice and Milan) on Frecciabianca is 27 euros. In general, the cost of tickets is higher for the higher speed trains such as Frecciabianca/argento/rossa and cheaper for Regionale which are slower trains stopping more frequently. The Frecce trains are also more luxurious (nicer seats and a/c always works) compared to Regionale trains.

Jenny it is a VERY good price! I paid more than that for a last minute trip for one person Roma-MIlano-Roma.

Once in Mestre you will have to take another train for a few minutes to cross the lagoon to Venezia Santa Lucia.

What a pain to get to Mestre (almost to Venice) and then have to change trains...luggage off luggage back on luggage off. Venice Mestre is the industrial mainland. Venice Santa Lucia is Venice Island (where you want to be). ItaliaRail does indeed show Venice S. Lucia as an option.

"I guess I didn't get those cheap tickets I hear about everywhere? You snooze, you lose! :)"

Oh my gosh! That's a long train ride for less than $50/person. How much cheaper can you get?

I expect that ItaliaRail has already delivered these to you as print-at-home tickets. Trenitalia.com does not sell print-at-home tickets for departures from another country; their international tickets require pick up at a train station in Italy. Standard, 2nd-class fare from Geneva to Venice is €110-120 per person.

You stated the price in dollars. Where did you buy the tickets? Does Italiarail sell in dollars?

When you're in Switzerland will you have a rail pass? If so, that rail pass will cover from Geneva to the Italian border so you would only need a ticket for the Italian portion of the trip.

At www.italiarail.com, you can specify $USA, $CAD, $AUS, GBP, and EUR. $193 total for four is a good price.

Okay, okay! I guess I did get a good deal! Thanks for your input, everyone.
Joanne, I don't have a Swiss rail pass. I just have the ticket from ITALIArail. I hope it's all good!

Personally for Italy we wait and get our tickets at a travel agent in Rome. They charge a nominal fee and we get the right thing. I have looked on the websites and I just can't figure it out. Other countries I have no problems but something about Italy is very confusing. I am sure if you did it all the time it would make more sense.