I can't remember which level the hotel rooms start at ... I've been on 27 before and I remember it feeling pretty low. The first rooms might be at 24 (??).
I was on level 22, with plenty of SQ crew (judging by those getting into/out of lifts). Also only booked for 1 person, but there were 2 of us at check-in which was not a problem, however it was when accessing lounge for breakfast we were advised only 1 person booked, so only one allowed and that "spouse stays for free" only applies to diamond members !! They let us in anyway, as as they knew my partner (diamond) from 10+ stays this year (and to answer the obvious, we booked under my name so I can retain gold, and get the EK bonus 5000 miles on offer at the moment). Provided written feedback using feedback form on checkout, expressing puzzlement at lack of upgrades etc, we'll see if I get a response.