I just returned from El Calafate yesterday. I was only there for a short stay but I highly recommend the Perito Moreno Glacier Minitrekking which includes a trip to the vista point. I also rather enjoyed the Todos Glaciares Navigacion boat excursion. I loved getting to see the Upsala glacier. I did a day trip to Torres Del Paine and the park was ravaged by a fire 3 weeks ago, so its in sad shape, although everything seemed to be open and running. The weather this weekend was absolutely stunning. However, it was extremely windy, so be prepared for that. I had the best steak of my life at Casimiro, the one that serves tapas. I reserved all of my excursions thru Aventura Andina, with the exception of the day trip to Torres Del Paine which I booked thru Amayco, the evening I got there and found it to be quite easy and was able to do everything I wanted.
I chose to fly Aerolineas Argentinas. It was much cheaper, and I actually thought it was rather enjoyable. I travel a lot and I personally can't stand LAN airlines and will do anything to avoid them, but I really think which ever you can find that matches your timing and price, go for it. Its only 3 hours.
Have a great time!!!