Hey I just got back from Europe a couple of weeks ago. I was with my husband for 2 weeks we bought our packs from Target the were 70 - 80 liter I can't remember exactly . Our packs cost $ 89.99 . We just took regular backpacks for our day packs and hooked them on the back. Our packs had the spine bar in them so they were wonderful support. We bought Eurail passes and they were great . We went to Dublin, London, ( Britrail passes for England) Amsterdam, Berlin, Innsbruck , Rome and Venice Italy. I liked the trains better than the bus. It depends on your budget. Go to
www.raileurope.com for prices or put in Eurail in a Google search and you will find what you need as far as that goes. I hope this gives you a start. If you have any other questions you can email me.
Chandy898@aol.com. I could probably answer some more since my trip is fresh in my mind. I can tell you some good Hostels to stay in with great prices and showers. Good Luck. OH about the backpacks they worked for what we needed. Other people spend so much on them and I just didn't think it was nessesary for us. All I carried was the clothes I was wearing so they weren't heavy.