I used to HATE flying so we have been all over Europe on the train. There are sleepers - boys absolutely adored travelling on them...the whole of the continent is incredibly well connected. Hi speed trains exist in LOTS of locations and you can get absolutely anywhere you could want to go (ish). Have a look at man in seat 61 for travel tips. Location - Italy, all the way. Hotels with Pools, beach if you want, gorgeous villas, stuff to do and see. Austria if you like the mountains and lakes - Croatia, Slovenia... Berlin and the surrounding areas, very child friendly and lots to do. We even went to Sicily on the train - that was a LONG trip but you can break it lots of times (Milan, Rome...) and the train goes on the boat. As a whole! Seriously, travelling by train is a lot easier than you fear. Obv you have to think carefully what to pack but your kids are old enough to pull their own trolly suitcase. And you don't need much for the summer! I say go for it!