I paid off my house a few months before turning 40.
Even if it wasn't the best choice in terms of savings vs. investing (and we're talking small differences regardless), it was well worth it to me. I grew up without financial security, and that has shaped much of my adult life. Knowing that my house is MINE, MINE, MINE is worth a great deal to me. With my house paid off, I can live on very little. Right now we're able to save fairly large amounts, but IF we were to experience a financial set-back, we might tighten our belts to avoid dipping into our savings, but we would be in NO DANGER of losing our home.
We are planning to build a small-but-nice retirement house just for the two of us when the kids are out the door in a few years, and the #1 goal is that it'll be an all-cash build. By selling this house and building on the land we've already purchased, we should be able to do it for very little money.