Multi country Itinerary help!

Here we go again...

Dorothy, I'll "start the ball rolling" with a few suggestions.

Rather than fly round trip to Frankfurt, have you considered open jaw flights (ie: return home from Berlin)? That will provide at least one more travel day, as you won't have to return to Frankfurt and spend the night. It appears that your trip is about a month long?

When you book your flight to Frankfurt, choose a flight that lands in the morning. It's fairly easy to get to Rothenburg as there's a rail station at Frankfurt Airport. The trip will take several hours, and you'll probably change trains at Wurzburg and Steinach. You can buy tickets in the Airport, either from machines or the ticket booths. I'd suggest taking a Taxi from the station to your Hotel in Rothenburg, as you'll be tired (keep in mind that you'll arrive in Germany the day after you departed from home).

For Verona and Padova, are you intending to stay one night in each place? I would definitely add at least one night to Florence. My preference would be to use train to visit hill towns rather than a Car, unless you're going to a location that's not well served by public transit. I would also add at least one and preferably two nights in Rome. Be sure to allow for travel times between each of your destinations.

One comment regarding Greek Islands - these typically shut down in the winter, so be sure to find lodgings that will be open. This is not the best time of year to be visiting Greece. My preference would be to leave Greece and Turkey for another visit at a more favourable time of year.

I don't have much information on the places you listed in Turkey, but I'm sure someone here will be able to offer some tips.

Regarding Hotel and Hostel recommendations, you mentioned that you were using Rick's books - there are lots of listings there for budget Hotels in various price ranges. If you want to stay in Hostels, check the Hostelworld.com or the HI Hostels site.

Good luck!

I should have mentioned that the amount of time and the round trip airfare to Frankfurt Germany is not flexible because we will be studying abroad in India before we go to Europe and our program set this up for us. So, time and airfare is set in stone.

OK, so first off, in Rome, the Beehive is an excellent hostel and they have private rooms too, if you can afford them. It is right near the main train station and is a really great place to stay. In Florence Ostello Santa Monica is ok, it doesn't seem like much when you get there, but it is clean, cheap, and has a kitchen that you can use to cook your own meals, though the staff is not the friendliest. In Venice, RoomInVenice is a cute B&B that was about 75 euro a night in high season, I don't know if it is open year-round. It was in a great location, and the owner was wonderful.
Now, the hard part. I think (and I am sure most people would agree with me) that you are going way to fast. I am a student too, and I just did five weeks in Europe, and I felt rushed whenever I only spent 2 nights in a place. I can't imagine spending only 1 night in a city. It takes a lot of time finding your hotel/hostel, checking in, getting settled, etc. Plus there is all the train travel time - basically you will be seeing more of the European train system than you will Europe. Sorry to be so harsh, but hopefully this board can help you fix your itinerary.
Of the places you are going, I have only been to Rome, Florence, and Venice, and I stayed in Naples, not Sorrento. I would recommend Sorrento though, as Naples is not a very nice city, IMHO. Rome has a lot to see, you are right with three nights there, but four would be better. Florence is wonderful! My friend and I were there for four nights, and we could have stayed longer, so again, I would suggest at least three nights. Venice should be ok with 2 nights, though I don't know about seeing both Verona and Padua on your way to Venice from Reutte - sounds like a very long day to me. Your two nights in Sorrento, with a third night as a ferry, should be perfect too.
I'm sure others can help you with the rest of your trip, but basically, the senitment will probably be to spend more nights in fewer places. Have fun!

Germany/Austria:

Rothenburg is a good choice - but you may be too tired to see it your first day depending on your flight circumstances. Reutte is one of Rick's rec's for visiting Neuschwanstein and the other Ludwig Castles - but it isn't particularly convenient to those castles by public transport, there's not much else there, and in my opinion, the castle tours and the castles themselves aren't very interesting or important.

Instead, I'd suggest staying in the Rothenburg area for 3 nights. You could visit the traditional Christmas market in Nuremberg, considered tops by many, Nuremberg itself is a vibrant and interesting place. And if you want to see a palace, Würzburg's Residenz is magnificent, and right next door to Rothenburg. Also, nearby Bamberg is a well-reserved city with wonderful atmosphere and nice pubs. In winter it's probably wiser to stay in slightly larger places than Reutte so that you have things to do if the weather turns on you.

Italy: You need 4 days for Rome and 3 for Florence, IMO, if you hope to see the things most people go there to see. The Archi Rossi hostel in Florence is excellent and does have some private rooms.

FRA: On your final night, Mainz is a more atmospheric spot than Frankfurt and offers easy transport to the airport. The Mainz hostel (Jugendgästehaus) is excellent, about a 20-min walk from the Mainz Römisches Theater train station, where you catch the S-Bahn to FRA. (At this station. a Roman theater is being excavated - hence the strange name.)

Overally, I think your trip sounds far too rushed.
I really think you need to cut something.