Based on schedules:
LHR-LAS starts first, aircraft is taken from another LHR frequency. Crew is PHX/LAS based (last year they were mixed as LAS doesn't have pursers trained for J as they only have long haul flights for CES)
ICN-LAS is 3rd-5th, returning 9th-11th - no ICN-DFW or DFW-ICN during those days. Crew is DFW based and deadheads LAS/DFW.
NRT-LAS aircraft is the one positioned in from DFW, likely DFW crew as well. Aircraft returns from NRT on the 12th, can't find what happens to it after.
TIL: AA has a FA domicile in LAS. I assume when you say crew base that's FA domicile only, no pilots. Had no idea AA had a crew base of any kind at LAS.
Always interesting to see where airlines have crew bases at non-hubs. pmUA was always interesting in having PHL (FA only), SEA (pilot and FA) HNL (also both)