In reply to Bounce Like a Fish:
I've never tried the Ecrins, but I always hear good things from those who've been.
Just to set a few myths to rest regarding the Dolomites that I keep seeing crop up on UKC. The majority of the routes are exceptionally accessible. I can think of at least 20 routes off the top of my head with a walk-in of under 30 minutes. Sure there are some more remote ones, but for me that's certainly part of the appeal and the approach is often is good as the routes. It also ensures the more remote ones can be enjoyed in relative solitude.
The wire conditions are also very good. KIA maintain nearly all the via ferrata's with the help of local guides and on the whole do an excellent job (bear in mind it's free to use any of the via ferrata). Punta Eterna, Oscar Schuster, Possnecker Path and Piz da Lech have all been refitted in the last year. Col dei Bos, Sandro Pertini, Ski Club 18 and Il Magnifici Quattro have all been put up recently and are super well equipped (as well as also providing quite a challenge).
The majority of the routes were put up during the first world war and so are exceptionally historical. Trenches, tunnels, gun emplacements, officers quarters, old field hospitals and lookout posts are all very common.
The Dolomites still have the highest concentration of via ferrata in the world (though it's actually Austria that started them). I'd recommend a look at
http://www.colletts.co.uk or
http://www.holimites.com/en/ , both excellent companies.