We didn't do the Cruce de Lagos trip, as we thought that it would be a bit quick (and pricey !) - instead we took the ferry across Lago Buenos Aires (or General Carrera, depending on which side you're on!), from Puerto Ibanez to Chile Chico, which was breathtaking - a fantastic bluey-green colour, with brilliant blue skies and biting wind. Well worth the trip if you find yourself down in that part of S America (and it's a long way down !).

Also wholeheartedly endorse the winery recommendations above. Dolium is quite an experience, as is Norton but at the other end of the scale !
We went for the 'public transport combined with a lot of walking' option, on account of we were on a very tight budget, but I can see the attraction of a car and driver.

What a great place - can't wait to get back again !

Stew