The olders love puzzles. Any kind of puzzle will get them going for a good half-hour — just enough time for Mom to take care of whatever needs doing around the house without (much) interruption.
One of their favorite games these days is this one called RUSH HOUR by Think Fun. The game comes with a bunch of plastic cars, a "road" and 40 puzzles for the kids to solve, the objective being to get out of a mythical traffic jam. They love it.
Personally, this sort of thing drives me nuts, so I’ve decided that they must have gotten this trait for problem solving their Dad. I’d much rather deal with "real" problems like how to translate grams to cups so my crepe come out right.