Graduation Trip to Europe

Flights and trains won't be a problem for 17 year olds (I'm pretty sure. Not every thing is the same so I don't want to blanket statement that, but all the flight and train knowledge/experience I have says you'd be fine as a 17 year old). I don't know what to say about reserving hotels though. If it doesn't work out, wait until the following summer. One year will not hurt!

I can't answer your questions for that age group, but I know of a source that might- the Let's Go series of travel books are written for teenagers and young adults. They may even have a web forum similar to this one. EDIT: It doesn't appear the Let's Go website has a forum. To answer another one of your questions, teenagers ride the trains by themselves all the time in Europe. Over here, they can't drive until they're 18 (and many don't even start driving regularly until they graduate from university), so it's one of the main modes of transportation for teens. You'll have no problems. I'm not certain about planes...

Daniel, plan for a solo trip. If others want to go, great. Good odds that both of your buddies will bail. It happens a lot. You will have no problems with planes & trains, but don't plan on using any cars.

Obviously your results may vary, but I found it quite surprising at how much I saw teens do in Portugal, at least. 16 is the legal drinking age there, and it wasn't just college kids staying in hostels with friends and going clubbing! (But please, if you aren't a drinker, don't feel like you have to just because you canI had to be the designated traveler some nights to make sure my friends were safe, because it turns out when you suddenly can drink legally and know you only have X days left to do so, it's easy to go overboard. Even if you aren't driving, it's a good idea to have one person always stay sober when you go out, especially if the group has young women; there are a lot of horror stories, but it's best just to be aware and street smart rather than afraid.) I'm sure you'll have a great time. Have fun, be safe, and congratulations on graduating :)

Daniel - I did post on your other question about staying in hotels/hostels but did want to give you one really big tip - if at all possible, book BEFORE you go. I have no idea if you are planning to go during summer (before you go to college?) but if you are and you are concerned about budget, good hostel locations, etc. - then do your research and consider booking your places ahead of time. When my daughter went with 3 other friends as a post grad trip they were traveling late May, early June. Even then they found that the really great places they wanted to stay (like the famed Beehive Hostel in Rome) were already booked. Just like anything else hostel travel has changed since I went to Europe as a teen. Now, with everything online, places do get booked ahead. And it is not that you won't be able to find a place to stay, it is just that my daughter and friends were on a tight budget. They really wanted the cheapest place they could find but they also wanted free wifi & laundry services. And some of the really popular hostels do pub crawls and other tours that are cheap and geared toward the young. They did find a good nate in Rome but the hostel they booked in Amsterdam was SEEDY and she didn't feel comfortable there. Their travel plans were maybe more set than yours will be, but they had family and friends in 2 places and they knew where they were flying in and out of, so 4 of their 7 cities were set as to when they had to be there, so it was really just a matter of figuring out where else they wanted to go. And since you have already planned at least one trip, you might enjoy the planning part just like we do - I never see it as something that inhibits me. I figure if I find somewhere on a trip that I REALLY wished I had spent more time in, then I can always go back. And that is why I've been to Rome 3 times and want to go back again!