'''If choosing something else:'''
You If the GPT is not (yet?) the right choice for than you can opt for the more established trails in the national parks. Check out the available trekking guide books i.e. the lonely planet guide "Trekking in the Patagonian Andes" from Carolyn McCarthy. This is how I started and what was the foundation to investigate and publish the GPT years later. The recommended I can recommend the following more established hiking areas in Patagonia are:
