I like layup shots that make you think. And I'd also argue you can't take the layup shot out of the context of the shots to follow.
To use par 5s as an example, many to me don't necessarily make the golfer think if he chooses the conservative route. It's simply: hit the ball as far as you can within reason so you can keep it in the fairway.
I like par 5s where taking the easier, more conservative route doesn't necessarily lead to an easy 3rd hot. Here's an example from a course I'm not that fond of, but I think it's one of the better holes: University Ridge (RTJ Jr.) near Madison, WI:
Here's the tee shot out of a chute (this is the way-back tees; the tees used by most players don't have nearly the chute-like impact this does). The hole bends a bit to the left, and then back to the right; fairway bunkers along the right side of the fairway are to be avoided if you want to reach the green in two:
Here's the choice faced by the golfer. The green sits up, quite a bit, from the fairway, as its benched against a hill that is the highest point of the course (and location of the clubhouse). The green, somewhat narrow, runs from front-left to back-right, angled away. For the player going for the green in two, the shot is a fade of sorts "slotted" into the green opening left. It's a shot with some risk to it, as bunkers long and left of the green, and another right, can catch the errant shot. The layup is pretty easy -- plenty of width for it here -- but then the third shot is a tricky uphill pitch over a large mound (the dark grassy area fronting the green right) to a narrow green. The further the golfer plays to the right with his layup, the more difficult the pitch, as the third shot is best approached from the left side of the fairway. I like this choice of a lay-up; the easier route (not going for the green) is not really difficult, but must be thoughtfully played, and still leaves the player needing to execute a decent shot for a run at a birdie/par. A sloppy 3rd shot could easily result in a bogey or maybe even worse.
Two looks: