Before anyone installs new tile I highly recommend a visit to a tile forum.

Before my recent tile job I researched a forum for several issues. I learned that professional tilers are crazy about the fairly new epoxy grout because it has a uniform color, never needs sealing, and it far superior to the old concrete grout. It takes some experience to learn to work with it and from what I've read, I don't think I'd want my job to be the first time a tiler uses that grout. The other negative is that it costs a lot more than concrete grout.

But there is a newer grout that is a urethane. The urethane never needs sealing and also has a perfectly uniform color. The urethane grout appears to be foolproof as far as installation goes. My tile guy had never used it before but said it is the easiest grout he has ever seen and it saved him several hours of work compared to concrete grout. He loved it so much he said he might start offering to discount the price of a job to offset the cost of the grout to encourage his customers to use it.

I've spilled plenty of things on it and it is absolutely impermeable.

The disadvantages of the urethane are that it cost 3-4 times as much as concrete grout. I think I paid $250 for enough grout to do a 350 square foot area. This product only came out a year ago, so long term performance (other than whatever the testing showed) is unproven. The pros say if you want white grout you may not want to use this, because it is not really white.