I found my own answer in the comments of the course recommendations for friendliness thread. Luke says:

It's really hard to find good writing on metaethics. My recommendation would be to read the chapter on ethical reductionism from Miller's [Contemporary Metaethics: An Introduction], my own unfinished sequence on metaethics, and Eliezer's new sequence (most of it's not metaethics, but it's required reading for understanding the explanation of his 2nd attempt to explain metaethics, which is more precise than his first attempt in the earlier Sequences).

On normative ethics, Luke says elsewhere:

I don't read much on normative ethics, but Smart & Williams' Utilitarianism: For and Against has some good back-and-forth on the major issues, at least up to 1973. The other advantage of this book is that it's really short.

But there are probably better books on the subject I'm just not aware of.

From what I see, he seems to attribute a similarly low significance to most of contemporary normative ethics.

Also, the Stanford Encyclopedia of Philosophy has been suggested twice, in case I do need to know anything in particular about normative ethics. I'll keep that in mind.

For posterity, as far as I can tell, the most popular undergraduate text on normative ethics is Rachels' The Elements of Moral Philosophy. The 7th edition has good reviews on Amazon. Apparently the 8th edition is too new to have reviews.