During the warmest months I usually switch from my Springfield Champion .45 to my old Star M43 in 9x19. Mostly because it's just less conspicuous under very light clothing, especially in that the pair of much smaller magazines "print" less and don't chafe rubbing bare skin under a tee shirt.
Both are carried in IWB rigs by Milt Sparks: VM II for the Springer, Summer Special with the Star.
No matter the season, my Keltec P 32 is in a pocket in its Don Hume pocket rig, too.