The couple that tours together, stays together. So it seems for McGraw and Hill, both 44, who hooked up during 1996's Spontaneous Combustion tour. Fifteen years later, the country superstars, now with their three daughters in tow, are still hitting the road. "I can't imagine it getting any better," McGraw says. "Aside from being able to do something I love for a living, I've got the best wife in the world."