Depending on what route you take you can make the journey in 3-5 days. We always take the path less traveled and opted for a route that not many tourist take. It is harder and takes a couple days longer but the vistas and trails are absolutely stunning. We extended our trip with a cushy start hanging out at the "Finca San Antonio" the day we arrived to the area. It was a great chance to tour the pueblo of Acul, one of the first military "model villages" during the civil war.
The Finca has a few guest houses where you can chill out and enjoy the Swiss-like surroundings. We got dropped off at the trailhead and started our 3+ hour grinder up into the mountains. It was tough but the views made it all worth while. We stayed the night a cool community hostal high up on the plateau and enjoyed an afternoon swinging in hammocks.
The rest of the days push further into the Guatemalan back-country on a myriad of braided trails criss-crossing the rocky plains of the alti-plano. The trek takes you through lush green valleys, steep ravines, plenty of remote villages into a place where time seems to stand still.
See ya on the trail!