I currently see, US flight Phl-tlv on J using AA miles available for date I need. I would prefer to book UA Jfk-tlv instead with AC miles, to save on infant charges. My question is, is it worth it to wait it out for UA flight to open up ? My concern is that, I might lose the US flight availability, and I'll be screwed either way. Or should I just suck up the $ and book the US flight ?