I have never been to a FROG event, but I belong to a camping group, the Volunteer Campers and we have at least one get together each year in the spring and occasionally have one in the fall.
Each year, someone volunteers to be the "planner". Sometimes, they will pick a theme and we all decorate our rigs to that theme or sometimes we don't have a theme. (One year it was bees!! I purchased some white LED C9 lights and dipped them in yellow paint, added some screen wings, used black pipe cleaners for legs and around the body for stripes. These hung on our awning until the storm came up. I also painted a welcome sign with our faces cut out of pictures and placed on painted bee bodies and had out name and "welcome to our hive" on it.)
We always have a meal together - usually a pot luck and with everyone bringing their own "meat" to be grilled. We have a grill master who will cook the brought meats.
We have also done pie iron dinners. Everyone brings things to fix in a pie iron and we share. (Manwich meat and bread is WONDERFUL!), canned biscuits with ham and cheese, biscuits or bread slices with pie filling,
We also plan a group campfire and we pool our resources for s'mores.
When planning, we try to get somewhere that takes reservations that are site specific so we can be close together; it needs to have some amenities such as a playground; needs to be in an area that has some type of local tourist attractions; be of moderate cost; if it has a group shelter area, that is even better.