Pre-plan your display on the floor. Determine the size you want for your total display and measure out that much space on your floor. Experiment with different arrangements until you have a look you like. Take a picture of it so you have a record to work from, then start hanging, working out from the center.
Use photo shelves. Many stores carry narrow shelving that works perfectly for displaying photos. You can set up three or four of these and then experiment to get the best arrangement of photos on the shelves. This also makes it easy to change out photos as new ones come along.
Keep frames set close together. For an effective grouping, don’t be afraid to keep photos close to each other. An inch or two between each is plenty of space. You really want the photos to feel integrated on the wall.
Use brown kraft paper or newspaper to determine your final layout. You can cut paper to the size of each photo and tape them on the wall to determine the best layout. Once you have your plan completed, just place nails right through the paper at the right spot for hanging, then tear the paper away. That way you know the photos will be set exactly right.
It may take a bit of effort to get your family wall finished, but once it is you can enjoy it for years.