The light bulb and the bridge riddle offer little insight into the problem solving skills of the interviewee: you either "get" the solution or not. There is not much room between the exact right answer and no answer at all.
The Boeing question on the other hand (like many other Fermi Problems [1]) might help you understand how the interviewee approaches a problem he doesn't know the answer to and whether or not he is capable of making sane predictions. But even though I think they are not completely useless, I expect a well prepared candidate to score better than some less well prepared, but in other regards superior candidates.