How to set up a family photo gallery so it looks decent?

Terry this website will give you a whole lot of different ideas and how to do this .

https://www.pinterest.com/pin/362399101247025091/

I would spray paint all of the frames the same color and then hang them up on one wall. You can cut butcher paper to the same sizes as the frames and then tape the paper rectangles on the walls to get the layout right before you put tons of nails in the wall.

Some ideas here: https://www.youtube.com/results?search_query=family+photo+gallery+wall

How about a family tree? Just draw a tree trunk and branches. Place the pictures on the limbs like leaves. You could paint the frames in shades of green or in autumn shades or just match whatever color scheme you are using in the room. These look amazing. I would love to have one but my tiny house just does have a wall that's suitable. Good luck and enjoy the design you decide on.

HANG each frame by fishing line & create a floating art gallery over head. Tape the bottoms of the frames to insure the picture doesn't fall out or anything first tho.

I would recommend choose one or two colors for the frames so it is cohesive. Then you can play around with different combinations on the the floor before deciding on one! Don't spread out the frames too much, something like 3-4 inches is usually good. I have some more tips for gallery walls here: https://www.makingmanzanita.com/gallery-wall-styling-tips/