Easiest Itinerary from Austria to Italy

Very straight forward 2 connection trip, about 10 hours with connections at Innsbruck and Bologna station.
Look at the schedule at http://reiseauskunft.bahn.de/bin/query.exe/en?country=USA
Tickets probably best bought at www.oebb.at/en

I don't see a safety issue with the night train (originating in Vienna) to Venice, just take necessary precautions. Store your luggage at Santa Lucia and spend the day in Venice, proceeding to Rome late afternoon.

My daughter just took a night train to Zurich, there were safety issues; or so the conductor told her. But he may have been misinformed.

Well, since all suggestions are welcome I would suggest you take the train to Budapest. The direct day train takes about 5 hours. Then after a few days in Budapest hop on Ryanair or Wizz Air or Vueling or Alitalia for a 1:45 hour trip nonstop trip to Rome for $110 or less.

Okay, don't want to spend a few days? Then take the morning train from Salzburg which arrives about noon. I know a guide that will pick you up at the train station, give you a whirlwind tour that will guarantee that you will regret not staying longer, but will get you to the airport in time for the 6:15pm Alitalia flight to Rome (arrives at 8pm which is plenty of time to check into your hotel. Of course you would be cheating yourself if you didn't at least spend a night............ maybe two??

The easiest option is a flight from Munich, but if you want same day trains these are your best connections.

RJ660
Dep 09:00 SALZBURG HBF (Austria)
Arr 10:54 INNSBRUCK HBF (Austria)

ECB 85
Dep 11:27 INNSBRUCK HBF (Austria)
Arr 16:20 BOLOGNA CENTRALE (Italy)

FR 9641
Dep 16:35 BOLOGNA CENTRALE (Italy)
Arr 18:28 ROMA TERMINI (Italy)

Yes, it's too far. Go to Munich and then fly to Rome. Flights are cheap and fast.

If you prefer the train but want to break up that 10-hour ride, I can vouch for Bologna. It's a large city with a huge historic district that is reasonably walkable from the train station or a short cab ride. From my experience, it is not a city you should arrive in without a hotel reservation, however.

We relish the long train day now-and-then. Even though it might be 10 hours, the machinations of flying might take you 8 anyway what with airport transfers, waiting times and delays. I think the train is always "easier." Go for it! We went from Fieberbrunn in Austria to Rome in one day in February. We enjoyed the trip very much.

Plenty of non stop flights Munich or Budapest to Rome. The time at each end of a train journey generally adds up to 1.5 hours. Doesn't have to, but in practice in new environments I think it's a fair budget for time. For air travel I figure 3.5 hours for early arrival at the airport and transfers to and from town. Again, doesn't have to, but in practice I think it's a fair budget for time. A 5 hour train ride takes 6.5 hours and that same trip by plane is 5 hours. Everything else being equal, i start looking for nonstop discount carrier flights when the train ride is 4.5 hours or longer.

But admittedly I don't LOVE train travel. If that's part of the experience for you or what you enjoy, then time is best spent on the train.

One thing to consider is cost.
Actual travel times may be comparable.

I agree train to Munich. Then flight with Vueling Air to Rome.
If booked far enough in advance, fares can be as low as 29 euro. Just make sure to read carefully their luggage restrictions.

The OBB site linked by Sam can sell you train tickets that touch Austria but won't be able to book the last connection which is wholly within Italy (www.trenitalia.com). Both trains and planes offer advance discounts, but flying will usually be cheaper for this distance; try www.skyscanner.com.