For Li, honoring that promise has become almost routine, and he spends part of almost every day scouring travel stories and tips online as he thinks about the couple's next travel adventure. In earlier years they traveled to most parts of China, but as Chinese turned their look outward, Li and Yang, too, became more adventurous, setting off for more distant parts. They are now planning to travel to France and the Netherlands.

"By seeing more of the world, my wife and I have become much more broad-minded," says Li, of Guiyang, Guizhou province. "It has benefited our relationship, too. We appreciate each other more after having done so many different things together."

A recent report by the online travel agency Ctrip said that about two-thirds of those age 40 and above surveyed traveled three to five times a year, and more than half of them inquired online about travel or made reservations online themselves. About 75 percent said they had grandchildren, but 70 percent said they did not have to look after a grandchild or that they only needed to lend a hand occasionally.