Sig's (i own a P229) are overrated and over priced in my opinion. are they good guns? yes. are they worth the "status" they seem to have? debatable. you are concerned about external safeties so that nix's the Sig in your book i think. the one feature my Sig has that i really like is the decocker.
Springfield's - i have no real opinion since i don't own one, never have owned one and have never even fondled one at the fun store. maybe another will chime in on this.
Glock's (i own a Mdl 22 and a Mdl 27) are, in my opinion, the AK of handguns. they are inexpensive, robust, easy to maintain and reliable. EVERY TIME i pull the trigger on one of mine, it fires. i cannot say that about the 20 other handguns i own. sure they have no external safety but there is an old saying that applies here......"keep your booger hook off of the bang switch until you are ready to fire". that is the most reliable safety you can ever have.
.40 S&W or .45 ACP? i think the .45 ACP round is overrated as well (ducks the rocks being thrown from the gallery! ). bigger is not always better when talking firearm projectiles (or rocks), but shot placement is. putting rounds center mass is the key and even the lowly .22lr will kill a critter just as dead. still, this is your choice.
since you live in the communist state of California where the right that shall not be infringed is infringed harder than it is out here in the flyover states, buying a pistol based on concealability is a moot point and seems to me to be a waste of time.
in the end, go try on all of the pistols that you are considering and get the one that fits you best.