Venice/Rome- If you are deciding between the two, that is a very tough choice. I would say do Venice now, because it is sinking into the ocean and may be gone within our lifetime (as we know it). You can go to Rome some other time (and you should). I studied in Rome for a month and it was incredible.

Venice-3 nights
-Buy a vaparetto pass. We did the 24 hour one. These are the boats that act as public transit along the canals. It is your cheapest option in terms of quick-ish transportation.
-Do not take water taxis or gondolas. They are wayyyy overpriced.
-Get on the vaparetto and take the grand canal route. This will take you around all of venice, so that you will get to see the whole city. It takes about an hour. Try and sit up front, it is way more relaxing than standing for the hour.
-When you get back to the main part of Venice, hop off the vap, and get lost in the city. Just meander around the city and see everything it has to offer. This is a very cool way to get a feel for the city.
-Go to Doge's Palace
-Frari's Church is cool
-Get a bottle of wine (or a box) and walk around the city
-See Rialto bridge and take some pix there

Florence-2-3 nights
-Eat at Napo Leone
-See Accademia
-Uffizi galleria is an okay museum
-Go up into the Duomo

Cinque Terre-2-4 nights
-Take the hikes, they are incredible.
-The hike from Riomaggiore to Mannorola is 25 minutes. It is easy and some of the best views you will have all trip.
-Take the hike from Vernazza to Monteroso. I am in terrible shape and the hiking aspect of it was pretty difficult. It is 2 hours long, mainly uphill, but the views are well worth it. I promise.
-In Vernazza, every tuesday morning they have a market, where locals pull up cars and sell stuff out of the back of them. It is great.
-Bar Centrale has some pretty good drinks
-La Lampara is a great restaurant with a little Italian owner who is so funny
-Go to the harbor in Riomaggiore
-Go to the beach at Monterosso (if you want to enjoy the beach). Rent chairs on a private beach. It is about 2 euros more than the public beach, but it is far less crowded.

Barcelona-3-4 nights
-Gaudi's Battlo House
-Parc Guell
-Cafe D'Academia is a cool place to eat, but you may have to sit at the bar if you don't have reservations
-Barcelona's beach front bar scene is really expensive. Everything is super swanky and overpriced (8 euros for a beer). The ice bar is okay though, but it is very small.
-There is a market district called Las Ramblas that is really fun to check out. Fresh fruits and a lot of candy and some other very bizzarre stuff.
-The Barcelona zoo is pretty fun, if you enjoy zoos
-Go to Cafe Granje Viader and get the swiss hot chocolate and some pastries. It is great.
-The beach scene is Barca is fine. It is super packed, and there are Indian men constantly walking by trying to sell you something. It is a topless beach if you are into that sort of thing
-La Sagrada Familia is incredible. Go inside and take the elevator to the top. Such an incredible view.
-Sagradi Euskal Taberna is such a fun place for dinner. They serve tapas and it is almost completely locals. You have to experience the Tapas when in Spain

Any other questions?

Again, my big suggestion is to buy Rick Steves Europe book. It will save you a lot of money, and will show you the best places to go in each city. Trust me on this one.

I've been to Europe 6-8 times between 1998 and 2008. (College to early 30s). Rick Steves has never let me down. I'm also a big proponent of at least 3 nights in each location. This gives you two full days to really enjoy and see a little more than highlights. Shrink your trip accordingly and just plan on going back. It makes the trip much more enjoyable and rewarding.

After graduating A&M in 1988, I worked in London for 3 months and then backpacked (trains) the continent for a month. I also took my wife on a 5-week similar trip in 1994, and have made more business trips there. Here are my thoughts:

Why so much time in Spain? Madrid & Barcelona are OK but in the scheme of things those would not be my choice. Spain is out of the way as well.
I would not do Amsterdam unless you are just into the drug scene.
With your current itinerary,I think you may regret not having more time in London, Paris, Rome, Venice, Salzburg or Vienna, and then Prague. These are just amazing places in Western Civilization and you need time to marinate in them, and see important places that may be on the outskirts like Cambridge or Versailles.
Get Rick Steves' books such as "2 to 22 Days in Europe" and make plans there. Do not make reservations as you will want to change your plans. Sleep on overnight trains to save time & money.

Actually, since you are doing a Study Abroad in Rome, plan to tour Italy on the weekends instead of while backpacking.

[This message has been edited by mefoghorn (edited 3/23/2013 5:33p).]

Hahaha thanks for the advice guys, but I took my trip last summer, and it was awesome. I was bumping this thread just to give future backpackers advice.

*******************DISCLAIMER***********************

*****FARMERSFIGHT NO LONGER NEEDS ADVICE(but thanks for the help)*****

Thanks FarmersFight! That will help out so much. I'm literally going to print out your posts and bring them along haha.

As for Cinque Terre, any suggestions on a place to stay?

We stayed in Riomaggiore, which I would definitely recommend. Check out tripadvisor.com for hotel info there. There are some really good recommendations and very lengthy reviews, so you can pick what suits you best.