As any road cyclist can tell you, nothing ruins a nice weekend ride like a flat tire. A vast majority of cyclists are not going to benefit from saving an ounce or two of weight. If you are not riding in the Tour de France, you are more likely to benefit from a tire that has a smooth ride, grips the road well, and doesn't go flat easily.
Enter the Continental Ultra Gatorskins. They are not the lightest road tires on the market, but they are virtually bullet-proof. They can take a lot of damage and lot allow a flat. I have literally ridden though piles of broken glass and emerged without any damage to the tire whatsoever.
The Gatorskins provide a nice smooth ride. They are quite forgiving on broken-up concrete, not allowing too much road chatter. They corner quite well, never giving me the feeling that I'm going to loose grip, even when turning through intersections at reasonably high speeds.
In the event that you do need to take them off and replace a flat, I have found them quite simple to remove. The bead around the rim is to overly tight, allowing them to be slipped off the rim with a pair of tire levers and a little muscle. If you've ever tried to replace a tire on a tight kevlar beaded racing tire, you can appreciate a tire that is easy to replace.
As for durability, they wear very well. I have am consistently able to get several hundred miles on a rear tire (which wear faster). At a reasonable price of about $35, they do not cost much to rotate out when the tread looks worn out.
On a slight downside, they are only rated for up to 120psi. If you are a heavy rider, you may have trouble getting them up to a high tire pressure. Likewise, these are not great racing tires, unless you are a casual racer or know that the course you're going to be on is filled with sharp rocks, glass and dozens of hypodermic syringes (in which case you may want to consider a different race).
For the casual weekend rider, you simply can't beat the Continental Ultra Gatorskins. They provide an excellent combination of cost, durability, puncture resistance, and grip.