multi-city stop in Europe

Richard: You certainly could make a quick run from Venice down to Rome and back to Salzburg. But it's really too much train travel time vs. tourist time in great cities. Rome has so much to see, and is worthy of 4 nights minimum. But any trip to Rome is going to be expensive. Your time would be best spent closer to Salzburg. May I suggest Munich as another great city to visit, and its 90 mile trip (from Salzburg) is easily reached by train.
Or, split your trip up and spend the night in Innsbruck where the mountain scenery is simply breathtaking.

thanks a lot. I will keep that in mind.

Richard, I was just looking up a run from nearby Salzburg to Venice. You can expect a 7.0hr journey on a train from Salzburg to Villach and then a bus from Villach to the Venice Tronchetto. I see fares of 49Euro. There is a night train that eliminates the bus but the overnight trip is much longer. Squeezing in Rome is really a stretch with your limited time. I'm not sure that there is a night train anymore. There used to be one from Venice to Naples with a stop in Rome. Not sure. But, the high-speed day train takes 3hrs12min. You can depart Venice at 6:13 and arrive in Rome at 9:25. Not bad. But, the trip from Rome back to Salzburg would take most of a day. Here, there is a night train from Venice to Salzburg. The night train departs Venezia Santa Lucia at 20:57 and arrives in Salzburg at 04:09. I can see this run on the Austrian website at www.oebb.at. Trenitalia won't display the run. That means, you would have to depart Rome no later than 16:00 to be in Venice in plenty of time to catch the night train.

I know it's not what you want to hear, but I agree that your time would be better spent closer to Salzburg. You could see Bavaria, Vienna, the Salzkammergut lake district or lots of other places, without the hours of travel time and the expense (you said you were watching your budget). I spent a whole semester in Salzburg back in the olden days, and your daughter will love it!

I would not discount going to Venice. If you want to go the night train route there is a direct EuroNight train leaving Salzburg at 1:40 am arring Venice 8 am. The cost is around 250 Eu total for the three of you with a 3 person sleeping compartment. Return after spending 1 or 2 nights at 1:30 pm with a single change in Innsbruck at 9 pm.
Its tempting to look at the map and say "We can go here,then here, then here, etc". Like a kid in a candy store, but someone is likely to get weary pulling up stakes every day and riding the rails 4 to 8 hours. Build up your wish list for the next trip.

When looking at night trains, keep the couchette cost and the time involved. I haven't checked prices, but is the night train cost less than, say, a triple room plus trainfare on the fast trains (which often offer no-refund, no-change tickets for advance purchases)? Also, in a short timeframe, will you have enough recovery time from night train fatigue (do you sleep well on trains and does your train have several stops to make?).

Thank you all for your help. If anyone has any further suggestion, please feel free to post it for us.

Venice is definitely doable. If that's where your heart is, try to go there. It's a magical city to visit. I would say though since you are pressed on time and money, I wouldn't try to include Rome. Maybe visit other things that are in between (or not too far out of the way) Salzburg and Venice, like Padua or Bolzano. On the other hand, like others have mentioned, you're in an amazing area. If you are not set on Italy and Venice, think about Bavaria (Garmisch-Partenkirchen) or Vienna and Bratislava. I loved my weekend in Bratislava! It's a fascinating city with a really cool old town section.