MIA-MEX-YVR-MEX-MIA - ride the JL 744 a couple of times; around 7550 mi; no plat bonus on JL segments unfortunately.
MIA-PHX-MIA-PHX-MIA - a long non-transcon, 7880 mi; good Q-pt and RDM yield, but all 738s.
MIA-PHX-LGA-PHX-MIA - 8241 mi, so almost as long as ANC; however MD80s on the direct (1 stop) PHX-LGA-PHX segments.