Okay, since we seem to have covered Germany and Austria a few years ago, and we've begun now on France and Belgium, are there any experts out there on optimal purchasing strategies for trains in Switzerland and Italy?

My specific needs:

1) a 2nd class 6-person couchette compartment on the no-change night train from Geneva to Venice.

2) 6 2nd class daytime tix from Venice to Rome, with a 2-3 hour stopover in Florence.

Traveling party is 4 adults (2 of whom are seniors) and 2 kids (ages 4 and 19 months). Willing to buy a seat for the 19-month old, though in the couchette I'm assuming he'll either sleep in his car seat or in the bunk with me or his mom.

We're still more than 60 days out on our schedule, so as I understand it we can't buy tix yet, but at 60 days, my current plan is to try to buy the Geneva-Venice tix via the Swiss Rail site (though it may have to involve an email exchange) and also at the earliest possible date get tix from Venice-Florence and separate tix Florence-Rome online at trenitalia.com. Best I can tell, on the Venice-Rome trips, I can qualify for a "family" discount since we'll have 2 adults for each child. I haven't seen any available discounts for the Geneva-Venice overnight trip.

Anyone see a better way to approach this?