Best way to travel on this route???

I assume you're going to do most travel from city to city by train? Start in Barcelona and go up to Madrid. Other cities T/B/A. Train to Paris. Train to Brussels and then over to Amsterdam. Fly to Vienna on EasyJet. Train to Prague Fly to Venice on Air One. Train to Florence. (Forget Pisanot worth the detour.) Train to Rome (Since you're so close.) Fly home from Rome FCO. Note: I didn't include Nice/Cannes. It's very out of the way, and would detract from your time in other better places. I included some budget air flights that'll also save you money over going on the ground. You can get down to Italy from Prague by air, but it's really tough to get there from Vienna; expensive and time consuming.
Your budget is a little constricting. We find rooms in many of your destinations to be higher than 70 Euros we like to allocate. You'll have to work hard to find budget accommodations. AirBnB.com and Booking.com are my best sources for inexpensive rooms.

Roda, I'd probably use an Itinerary along these lines....... > Flight to Madrid > Train (AVE) to Barcelona > Flight to Nice (I'd skip Cannes). Have a look at Vueling for flights. Use Nice as your base for trips to Monaco, Eze, Villefranche, etc. > Train to Pisa (about 6 hours with 2 changes, which is reasonable). > Train to Florence (about an hour or so as I recall) > Train to Venice (Venezia Santa Lucia) > Flight or train to Vienna (if using train, I'd suggest stopping for 1 night in an intermediate location to break up the journey, perhaps Innsbruck. With flights, I wasn't able to find any low cost direct flights on that route). > Train to Prague (about 5 hours, there are some direct trains) > Flight to Amsterdam (I'd suggest EasyJet - if you book early, you should be able to get cheap prices) > Train to Brussels (about 2 hours) > Train to Paris (about 1.5 hours) > Fly home from Paris Note that the travel times by train may vary, depending on which stations you use. Many cities in Europe have several stations, so it's important to know the correct ones to use when planning rail trips. WHEN is this trip taking place? Good luck with your planning!

Thank you so much for the info ! We have family in Nice and we are staying with them so that's why I wanna see everything that is in that area . We want to use hostels and surf crouching if possible . The trip is for next summer, June - July 2014 . I forgot to add we want to go to Alsace, France...friends there to visit and stay . Are the overnight trains cheaper then flying ?

Why fly from Barcelona to Nice? Is't pretty close so train is not cheaper ? If I fly in Barcelona and out from Paris is not more expensive then from the same city ? Thanks again for your help and your time ! I really appreciate it ! We already did something similar 2 years ago but it was not planned at all so I hope we save some money this time .

While in Nice with your friends, be sure to go see Monaco and Villefranche sur mer. I agree with previous poster that Cannes is not too exciting.

Flying into Barcelona and out of Paris won't be more expensive than a round trip to one city or the other - it could even be cheaper. When you look at flights, choose the multi-city option, do not look at two separate one-way flights. It can be a real timesaver, too, allowing you more sightseeing time because you don't have to backtrack.

Roda, The rail trip from Barcelona to Nice ranges from 8.5 to 17.5 hours, with 2-4 changes. I haven't checked the prices, but doubt very much if they would be less than a budget flight booked well in advance. A flight is a much more efficient use of holiday time, especially on that route. Cheers!

Thank you all for the info and recommendations !!! What cities do you think are worth visiting in Spain ? We visited 2 years ago Barcelona for 4 days and my husband visited Marbella for couple of days early this year and he liked it . Thanks again for all your time and info !