Spain: Barcelona - You can drink a lot of sangrias in a relaxing atmosphere, then stroll the beaches or city without paying for transportation. There is also nice architecture, great food (walk a few blocks into the residential areas and you'll pay half what the tourists are paying), women, etc.
Italy: Travel from the Venice train station to less known towns such as Sirmione or Desenzano for less than 10 euros and 45 minutes of your time. Those places have great cafes on cobblestone walkways and have a beautiful view of the alps (especially after a rain when the sky is less hazy from pollution). Other great places to go near Venice are the dolomities, and if you want to travel further go to Lake Como, Cinque Terre, or the popular cities such as Florence and Rome. If you have a vehicle, than a few hour trip over to the Croatian islands will be awesome if you like the beach. The water on that side is much clearer, and the islands are beautiful near Rijeka and further south.
Elsewhere: If you want to exit Italy, then travel to Milano on the train from Venice then get a connection to Interlaken, Switzerland. The swiss alps in that area are one of my favorite places in the world (specifically Lauterbrunnen). That train trip might set you back about 50 euro or so, but you can spend the night in Interlaken at awesome hostels for cheap. Another place to go from Venice via boat (or Bergamo if you fly) would be Corfu, Greece. It's a beautiful island with friendly people and crystal clear water. I rented a scooter there for cheap and travelled the entire island for weeks, and it was one of my favorite "relaxing" vacations.
I hope this helped! I'm a 28 year old American who lived in Europe for many years, and have travelled to 45 countries... so hopefully you can at least find one recommendation useful! Enjoy your vacation, and message me if you need any info/help.
