I think a floor puzzle may be more useful that size. We have a Melissa and Doug one (http://www.amazon.com/Melissa-Doug-World-Floor-Puzzle/dp/B0007ODGTQ/ref=sr_1_1?ie=UTF8&qid=1428365517&sr=8-1&keywords=melissa+doug+floor+puzzle+world) that has the pieces cut into the shapes of the continents. It helps my 5-year-old to manipulate and fit together the pieces.
If you want something for your wall, I would go with a regular laminated 3’x4’ world map.