Depending on how often OP would be flying on SQ, would it make sense to use the SQ FF program for *A and enjoy PPS benefits? The revenue requirement would be fairly easy, even though IIRC only FC and business class on SQ counts. OP would lose the possibility of domestic FC upgrades and free Y+ on UA flights, but it sounds like that won't matter. SQ miles seem to have reasonable availability (plus waitlist requests) for SQ award flights and upgrades, although the obvious drawback is that SQ miles expire. IIRC having *A Gold status on a different carrier is good for UA lounge access on domestic UA tickets, or do I have that wrong? Of course, a lot of the SQ vs UA comparison depends on whether OP would get UA GS or not.