Have you done any looking around for gallery wall inspiration? There's a bunch out there. If you haven't I would start with that. I would use all the same color frames to keep it cohesive. Is your largest photo an 11x14? Small photos can start to look very busy on a wall. I would try and stay with 8x10's and larger. If you're going to use a 5x7 I would mat it and use a larger frame like an 11x14. Another way to use some 5x7s would be to get a frame like this. They also have it with 4x6 photos but think larger ones would be better visually. I would mat almost everything. This all can get expensive fast so I'd get the frames you want and if you were going to try and save anywhere or do it a little as a time, you could always place the photo (s) on top of white paper (tiny piece of painters tape on back of pic). It will read like a mat and from a distance it looks fine. I've done this just to get things on the wall and then later picked up mats when I could.

I prefer and have symmetrical gallery walls. It's just my personal preference but I also think it's harder to pull off asymmetrical and it's rare I see one I think looks nice.

Move your frames around on the floor to get an idea. Get some posterboard and cut out the frames then put painters tape on the back and get them on the wall for a visual. It's easier to adjust and go from there. You can also post the mock ups on here and I think it may be easier for us to help.

Most Houzzers would suggest that personal photos aren't the first thing you want guests to see when they enter your home. They know you live there; a photo line up isn't necessary to prove it. Besides, most of your items are too small to be appreciated from that distance and the railing prevents closer inspection. I suggest you get your family together at the next optimal occasion and have a professional photographer take a family portrait. Have it professionally matted and framed and hang it in a more private area of the home like the family room or even the master bedroom. In this spot, I'd put a big colorful piece of art that shows off your personality.

Yes, I forgot to mention almost everyone here thinks photos should be banished to a bedroom. This is one thing on Houzz/Gardenweb I've never been able to wrap my head around. To each their own but for a long list of reasons I vehemently disagree with this idea.

I personally love family pictures in a home. The first poster gave good advice though. Smaller items tend to look cluttered faster. Use larger frames, or mat smaller pictures, and try to use the same style of frames for all. Then get pieces of paper and tape them up until you decide on the layout.