What’s the best way to do budget travel in Europe?

We’ve been starting to think about the whys & wherefores of our European travel…what’s the best way to travel around as a family of five on a budget? There’s the possibility of rail travel perhaps, with a family rail ticket. Or would it be better to rent an RV? Or as one traveller suggested, buy an RV instead. Or do we just drive and pack our tents? To be honest, the more I look at options and prices, the more I think it might just be cheaper to get package deals, or fly and stay in great hotels! By the time you pay for the RV, and then the gas (which is more than double the price of ours in Europe), and then you pay to park it somewhere, I bet you’d more than cover your plane tickets and hotels! Not as adventurous, perhaps, and not really what I have in mind for my year of travel, but seriously, it might actually be the cheapest option in some cases!