As a recent first time gun buyer, I can say there were a lot of choices to be made. The best thing to do is to actually go to a gun shop (regardless of whether you are buying it there) and hold them. I have small-to average sized hands for a guy and it shows when I shop for guns.
But you should definitely choose a caliber that fits your needs, then a platform. I looked at alot of guns and held alot, but I decided early on that I wanted my first gun to be a 9mm. I also knew I wanted a semi-auto or a bottom-feeder as I see them called a lot around here. I held alot of guns and originally was attracted to the polymer frame.
Price was an object though, I didn't want to break the bank, so I set a limit of $600 for myself. That ruled out a lot of good guns, but left a lot of good ones.
I had it pretty much narrowed down to a Springfield XD and a S&W M&P. I shot them both. I really liked the backstraps on the M&P and they'd probably be really good for your family.
But then I bought a CZ 75b. I held it, I pointed, I didn't fire it. It just felt like my gun though, and the price was right. I walked away with it and I was very happy with it the first time I shot it. I'll definitely get out and shoot it again this weekend.
I'm new to everything gun, and I'm not biased by reputation or years of experience. I really think it comes down to what feels the best for you. Are you looking at the 5.7 just because it is high cap and shoots a cool round? Are you looking at .45 because it's a 'real mans' caliber? Don't get me wrong, I'm not knocking those as reasons. But you really need to think through this decision, because it can make or break how much you enjoy future handguns.