It's pretty frustrating to see that d20 appear over your head and then you fail the check. And then you have everyone else in the party come over and they also fail their checks. You know that something is going on there (which you probably shouldn't), but no amount of digging through things will let you find it (which it probably should). This feels really bad.
A couple of rough ideas that could be useful in some combination:
1) I'm sure someone has said this before, but don't show the die rolling - just tell the player if they succeed. That way, you don't know what you're missing. Maybe have that check trigger from farther away so all of your characters are more likely to hit it by accident (since you won't know to bring them over).
2) The hidden switch is always present, but there are things obscuring it. A successful perception check will call attention to the fact that the stack of crates (in front of the switch) is oddly far away from the wall, but doesn't actually show you the switch. It's up to you to put in the final bit of work to find the switch. Messages could be proportional to how good your perception check is, i.e. No information at all vs. "Something about the size of this room isn't right." vs. "Something with that wall isn't right." vs. "There's probably a hidden room behind that part of the wall. That bookcase is oddly conspicuous."
3) <this space reserved for the idea that I forgot while typing up the other two>
Perception checks are terrible. Hard to believe that of Baldur's Gate games did it so much better. It is really bad when one of your party members finds something but you can't find what it is, but it's worse when its a trap
