To pile upon what everyone else has already said...given that we recently flew to Asia in UA C (thank you SWU) and within Asia on SQ/TG in C (no F segments).

EWR-NRT (UA C)
NRT-HKG (NH Y)
HKG-SIN-DPS (SQ C)
DPS-BKK-HKT (TG C)
HKT-HKG (TG C)
HKG-EWR (UA C)

On all of those flights, not a single meal was offered (or requested by us) to our daughter. UA [naturally] was by far the worst service wise, and didn't even offer to stagger meal times so that my wife and I could actually try to enjoy our meals serially.

TG and SQ went above and beyond on all of those flights and offered bunches of toys to our daughter, while UA pretty much gave a shake of the head and no difference in service in the slightest bit. On NH, they gave us the bulkhead (in Y) and tried to cater to us for timing/baggage, but nothing else.

We tried to give our daughter some of the food (vegetables/grains/some of the protein) and got our drinks to benefit her (juice/water), but we also came prepared and had bunches of food and milk (purchased by us) brought on board, especially for the 15hr HKG-EWR flight.

You should really not expect much from UA (or SQ/TG) for the infant fare. Yes, it's ridiculously expensive (ours was US$360 [I believe] for the HKG-SIN-DPS-BKK-HKT-HKG, and I thought THAT was expensive) and UA is surely pocketing money for not having to do anything at all...and they love it and hoped more people would do the same, but you aren't going to get anything out of it.

We've had good experience with service on LH, AC and TK in Y, but not ever served a single meal for our lap infant daughter in any class on any trip.

As suggested by others, If I were you, I'd fly with 3 seats in C...but for us, this wasn't an option. I wasn't going to buy 3 seats in Y to use up 6 SWUs...and there weren't 3 seats for awards...so it was a simple decision for us.

Good Luck and Enjoy the trip, but seriously, don't expect much from anyone, ESPECIALLY UA.

-jeremy