In Australia, I've never seen anybody get done for having carry-on luggage that's too big. It's pretty much whatever you can fit in the top compartments. In fact, I've seen people carry more than one hand luggage.
I'll be going to Europe soon and plan on taking a flight whilst there (Nice to Venice on EasyJet). So I think I'll buy one checkin 20kg bag. I don't think I'll need anymore as that's probably quite a lot but I have noticed that any extra kg above 20 kg seems to start to incur a lot more cash (esp. if you buy it at the airport). So if I do get to a position where I'm a little bit over, I'll be looking to find ways to store as much into my hand luggage as possible.
So just wondering, what are the airlines generally like in Europe? Are they fairly strict on ensuring that the size and weight of hand luggage is within their limits or are they fairly relaxed just as long as you don't try to bring an elephant onboard?