How about the train?

Retiro Station

A trip is made up of planned situations, inevitable surprises and pleasant discoveries. This is a section to share those little or big secrets that only the real experience of travelling allows you to unveil.To start, here's a bit of information that, though accessible to everyone, nobody seems to be aware of. In Argentina you can also travel by train and, despite what many locals will tell you, not only survive but actually enjoy it.
Travelling by train may take a little longer than going by bus but it's also much more comfortable and even cheaper. You can sit in the dining car, stretch your legs and sip your favourite drink while talking to a friend, to the author of the book you're reading or to yourself or just look out of the window and see the world pass by: a tree, a cow, your thoughts. A kind of meditation accessible to all.

See Fares and Timetable

Mar del Plata can be a good destination for your first trip (provided you avoid the summer crowds). It's a lovely city, only six hours away from BA. The best place to try a delicious chupín (fish stew) and watch the happiness of the fur seals as they sight the first fishing boats coming into port.