Originally Posted by
thom1033
Biggest question: I currently have these held as two separate itins on AA. Assuming I book before the hold expires, I am good on the award availability, correct? I don't want to assume it is held then lose the award seat!
Definitely don't let the hold expire! Sometimes you can extend the hold (i.e. hold it again) if you're not quite ready to book. Call and ask.
Secondary questions:
1) Do I have to clear customs/immigration in YYZ if I'm only connecting through? What about LHR? Can I explore London for the day?
Definitely leave the LHR airport and visit London. The passport people will be quite pleased that you chose to visit and explore their country during a long layover.
2) What lounge access will I have in LHR? (AA plat for what it's worth)
One-world business-class lounges because of your status ; one-world First Class lounges because of your F-class departing ticket.
3) Any suggestions on something to do in London with a full day layover?
It all depends on what you like. Whatever you're in to, London has it.

Go to Tripadvisor and look up "Things do to in London". It will show more than 1000 things to do. Scan just the top ten percent and find something that interests you. By staying within the top ten percent (as rated by your fellow travelers) you're almost guaranteed to make a great choice.
4) Any easy, reasonably inexpensive, say sub $150, airport hotels at JFK?
use hotelscombined.com to scope one out.
5) Anything else I'm not considering?
I don't quite understand why your LAX-LIT flight requires routing through JFK. Surely there's a better way to get from LAX to LIT. While we're on the topic, I wonder if other outbound routes are available (i.e. through HKG, PVG, NRT, HNL, PPT). Sometimes (often) you have to specifically guide the AAgent to search through the various options ... or search it yourself on Qantas website (requires registration).