Most of the time it comes down to $ though. A place may not be one you have any interest in matriculating initially, but then you see what kind of financial aid package they offer as compared to the place you were leaning towards and suddenly you don't want to be too quick to judge. because of all these moving part, I have no problem with people holding spots up to the date they must choose. If it's just collecting feathers in your cap then sure, you should withdraw, but if there's a $ amount that could make a place in the running, then by all means it on the spot until that gets sorted out. Nothing "unethical" about this. And no, it's not "unfair" to anyone because the person next on the wait list is still next, whether you relinquish the spot early, or in May. That person my not be happy sitting on the wait list longer, but he doesn't get harmed by waiting.