Sigs are great guns, very reliable and well made. Just keep in mind, some people do not like the double action pull on the first shot and single action thereafter (been a while since I bought one, perhaps some models/actions have changed).
H&K makes some nice solid reliable handguns, along with Kimber. Personally like the grips and "weight and feel" on a 1911 style pistol over a Glock, but have a Glock as well, and it's one of those few guns that you could take in the woods for years, never clean, get it dirty, shoot any type of ammo, and chances are, you'll never have a misfeed.
You mentioned that girlfriend and child may shoot the gun as well. Keep in mind, only my opinion, there is always a tradeoff between caliber and pistol size/weight. Smaller/lighter the gun, more recoil. Can make shooting non-fun for beginners and not want to shoot.