So much advice!! Lol. Thanks everyone so far for your contributions! I'm actually finding it quite hard to plan this trip.
I'll get the more utilitarian stuff out the way first :-)
*I'm an experienced back packer, but I've only done Asia (backpacking). So I have all the gear, like an awesome pack with detachable lighter backpack
*I'm a Kiwi and also have a UK passport. I think this may make some things cheaper for me (as I can claim to be a citizen of the EU I guess, so long as they don't ask for proof of address), but still researching how much actual benefit I will have from this...
*I work in a bank, so I get subsidized travel insurance, a no-transaction-fees ATM card & credit card (with PIN & chip, we only have these in NZ)- WAHOO for work perks!
*I've heard couchsurfing can be awesome but I've also heard of near-literal horror stories... especially as a woman, I'm a little nervous about this... any ladies about there have any thoughts about this? I am very capable of defending myself (hurrah for self-defence in NZ girls schools, a few boxing lessons and older brothers lol) if needed but don't really want to be in the position where I need to if I can avoid it...
*I'm not that fussed about flying versus trains so long as I'm not wasting a lot of time. Does sitting in an airport awaiting to clear customs count as wasting time? To me, it does. I hate these periods. At least with a train I'm still technically moving and I can watch the scenery right? And trains are faster than buses, plus I think more comfortable? (correct me if I am wrong about the comfort, I live in the South Island of NZ and our trains are only for tourists here, so I am NOT speaking from experience) But maybe I should get individual tickets rather than a rail pass...
*I LOVE the atmosphere of a hostel :-) I have never failed to make lots of friends while staying at a hostel, and I think that's a big part of the fun on an awesome trip like this!
*I used to speak fluent French and although rusty, I believe languages are like riding a bike... you never forget. Last time I was in a French-speaking country I was speaking reasonably OK after 2 days. So I hope that this will be a useful skill!
*Since a few people have mentioned it- I said Carcassonne because I spent 6 weeks every summer in the South of France when I was a teenager. It's an area filled with memories :-) But it was just an example, there are lots of towns/villages/areas I will visit but haven't mentioned because to most people they won't mean anything. The leg from Barcelona to Paris is one where I will take my time if I can.
What I want to do:
*I'm still young enough that I want to go out and 'party' and drink and bar-hop. But I'm old enough that I don't want to do it every night- or even every second!
* I love immersing myself in the local culture. So for me, this means sitting and having a glass of wine on a street corner and watching the world go by. It means walking around looking at the architecture and going to the markets and listening to everyday life. It means that if I am in a park and there's an aerobics or dance class or whatever going on, I join in.
*I love museums, castles, churches, art galleries and other places of historical note. I can't get enough of them. I was the child who you couldn't get to leave until they had done every interactive activity and read every plaque. I still am!
*I have a sense of adventure, so I like going off the beaten track, trying new activities and I'm not too scared to try anything adrenaline filled either...
So I need to incorporate a bit of all of the above in this trip!
Where to go
Awwwww this is the really hard bit- trimming the fat, as it were. I really want to fit them all in! Even this list cuts out HUGE chunks of where I want to go. But I know I may need to. Still looking at this, but if needed I will look to cut out the Eastern side as it is the logical step.
I still want to do the full itinerary but considering this:
Amsterdam, Brussels, fly to Naples, travel from there via train up to Rome, Cinque Terre, around the Cote d'Azure down to Barcelona, back up to Carcassonne, and then on up through France stopping off here and there. A couple days in Paris (I have been maybe 6 times so don't need a very long time there, perhaps just 2-3 full days), and then Eurostar to London and finish there instead of start? I looked into it and it would be cheaper for me to fly into Amsterdam too.
Thanks to the people as well who mentioned the main in seat 61...