Originally Posted by
rbphilip
In fact, I believe I'm obligated to do so as a US citizen and resident.
That is the common wisdom, but it may not be 100% true. I don't know if the law technically compells you to, but the CBP/State FAQ (don't remember which) says you
can enter on another passport but shouldn't. I believe you also aren't entitled to consular protections from the country of the passport you enter on if you are a USC