the way I see it opt #1 & #3 are out since the OP would be paying .15 per UA mile and .10 per AA mile with LAN
quick TransCons can yield the OP at least 2x the EQMs for the same $$, over 3x with UA or US. Heck Im sure $1600 spent on transcons can yield 25k if done right
as for #1 not all TO tkts are able to earn Miles