Train is definitely the best way to travel around Italy.  Either look for a cheap intra-Europe flight or take an overnight train to get between Vienna to Venice.  There are dozens of trains each day to choose from between the other cities.  Venice to Florence is less than 3 hours and Florence to Rome is less tha 2 hours on the fastest trains.

Rome or Vienna is probably the best place to land — because you’ll probably find the biggest selection of flights and probably the cheapest flights.  I would look for an open jaw:  Into Vienna and out of Rome or vice versa.  If an open jaw doesn’t work out pick which ever city you can find the cheapest flight or a direct flight.  I believe there are direct flights from Detroit to Rome.  I doubt you will find any direct flights to Vienna.  Another option is to fly to whichever European gateway is the cheapest — London, Paris, Frankfurt, Amsterdam and take a cheap European airline to get to one of your cities.. 

Thank you for the quick response. Can you pls tell me if there are any websites where I can find cheap air tickets within europe. I looked at travelocity & hotwire and they seem to be expensive within europe.
 
Thanks
 
rsk

Use www.whichbudget.com to find the cheap airlines that serve your destinations.

Go to the “cheap flights” forum on this site for lots of tips and help finding flights.  The low cost European airlines don’t show up on the standard searches.  Also look at They offer a $99 pass for some flights.  Even if you don’t use the pass you can see which European airlines fly the route and then look at the airline’s website. 

Thanks again. I found a round trip ticket from Vienna to Venice for 54 Euro with Sky Europe. Is this for real. Is this a decent airline.
Also if I have time only to visit one place in Austria which one should I pick – Vienna or Salzburg
 
Cheers
rsk

Yes, it’s for real.  There’s been some discussion about sky europe on “cheap flights.”

Yes, it’s real.  There is/was a sale on SkyEurope recently.  I got a ticket from Bucharest to Budapest for 1 Euro + taxes.  I think it came to 15 Euro total.