Well like Spidy said Glocks are the number one police gun for at least one reason, simplicity. Cops are notorious for not cleaning their weapons. Glocks are simple to operate as well.

Spidy said 9mm and or 40S&w. Both good choices, but If your wife is very recoil sensitive, a Glock might recoil to much for her (although HIGHLY doubtful).

Personally I like 45acp. BIG hole, recoil is not "Snappy" like the 9 or 40.

Any name brand auto will do you good. Glock, Sig (my fav) and I personally like Springfield armory over Colt in a 45acp.

Main thing, IF you can, handle AND shoot the weapon or weapons you are wanting to buy. Also break each one in for about 200 rounds, clean or get it cleaned back to as unfired shape, oiled up and then run another at least 200 rounds through it without a failure to funciton! Then you are ready to trust your life to it.

Spare Mags. I prefer six for each weapon. DO NOT BUY CHEAP MAGAZINES!!!! Most failure to feed are from faulty magazines. TEST EVERY MAG YOU BUY FOR RELIABILITY.

And remember, being MACHO and carrying a 45acp, 44mag or what have you will do you NO GOOD if you flinch every time you fire it. Also consider how fast follow up shots can be made.

Good luck

Randy