No parent would prefer to send a child to Disney World over preventing even a single one of his or her children from contracting a life threatening illness!

This kind of criticism seems inappropriate to me. It is so utterly obvious that foreign lives could be saved for less money than a trip to Disney World, that it should be an automatic conclusion that people who donate to Make-A-Wish are deliberately purchasing fuzzies, not attempting to purchase utilons. In other words, I highly doubt that people who donate to Make-a-Wish are doing so because they think saving a foreign infant's life would be more expensive; rather, they're most likely doing so because they actually want a domestic sick child to go to Disney World.

Your argument is not an argument against donating to Make-a-Wish; it's an argument against going to Disney World.

This is why I tend to be impatient with discussions of optimal philanthropy; most of it seems to consist of attempts to get people to feel bad about doing things that make them feel good. Of course I realize that this post, despite appearing on LW, isn't actually targeted at a LW audience, so maybe it will have some effect just in terms of getting people to think about utilons when they might not have otherwise. But for me at least, the case is pretty much closed at once: when you're actually trying to be efficient with your money, as measured by utility, you should spend your marginal dollars (or whatever currency) on existential-risk-reduction/long-term-species-improvement. The utilities (positive and negative) involved in these domains are so large that, until you actually think existing institutions are having a satisfactory impact on these problems, nothing else even comes close.

Hence I don't myself see a lot of need for arguments about whether saving lives in third-world countries is "better" than going to Disney World -- or sending a sick child there.