we can get very good deals on flights and it would cost a lot more by bike but that would be the holiday for me....been thinking about it for a few years now,you get a good view of france and italy from the plane and i would rather be on the road enjoying the scenery.........about 2000miles and as steverist has already mentioned "you only live once"..........biggest worry is doing it on my own,be nice to have back up if i have any problems 
One, is never going to be enough.....