I can advise you what to do based on what we did... For our honeymoon in October (several years ago) we went on DL from ATL to SFO. SFO to NRT on UA(husband's dad worked for UA). We could have gone to NRT direct from ATL but thought we had a better change of FC on UA. What we didn't understand is that we were not allowed to travel in FC, with 3 classes of service. There were seats in FC (we were actually assigned two lovely FC seats and the boarding passes were ripped up by a supervisor). No seats in BC so we sat in the middle, in the back -husband actually tried to deplane, not a great start to a honeymoon! Totally our fault for not knowing the rules.

In NRT, got stuck, we were told we wouldn't get out for 4-5 days on UA, told it is always full, so we bought tickets on NW and got to BKK. Came back through BKK to NRT, then to ORD, then to ATL (got stuck in ORD but that could happen anytime).

Weather was great in mid October. I've been in mid December and the weather was great then as well but as I recall, parts of the region have their monsoon season at that time but I think it's the east coast??