This is pretty epic, I needed to fly to the states for meetings in DC, Seattle, LA and NY plus I wanted to see my sister in Claremont, CA.
I just used miles to book EZE- IAD - ONT then LAX - SEA then SEA - EWR then EWR - DCA then finally DCA - EZE on the same web page for a fraction of the miles it would have cost me doing it all piecemeal.
United is definitely the new airline to have a frequent flyer program with. Delta and American can go EABOD. I guess the downside to the awesome new route map is that Service blows on both Continetal and United. But it blows across the board so I guess thats a wash.