Personally, I can't see why taking the infant in F versus Y should be a problem. I don't fly F all that often, but the child near me in F last Thursday (LAX to DEN) didn't bother me. Then again, I do like children and find myself often frustrated with the sentiments of those who are more hostile to the idea of babies traveling on planes (even though I have none of my own). Flying in F should actually bother fewer people should your child become unhappy on the flight, though those people are likely to be more frequent flyers (who should be more accustomed to the situation!). And, you'll have more room to keep your child comfortable.

Friends of mine who have traveled with children say that this is actually a good age to be flying with babies. They're finally on a regular schedule and sleep for long periods (YMMV, of course). In fact, the couple of which I am thinking was traveling from PHX to TXL, so their experience is pretty relevant.

And, congratulations to you and your wife!!!

P.S. But, maybe this should be on the "Traveling with Children" forum? I can't see that this is too United-specific.

P.P.S. Woo-hoo! My 90th post!