It’s very family friendly. I’ve exhibited MOCs at BrickUniverse events in Dallas and Raleigh. The public days offer considerably more themed play areas than other events – instead of just one or two “Stay and Play” type areas, there have separate ones for “Friends”, “Star Wars”, and “Architecture”, as well as the monochrome sort you see at Kids Fest events and the common DUPLO play area. There are also non-LEGO activities (an inflatable bounce house of some sort and caricature airbrush artists) as well as public-facing seminars about LEGO.
If you do want to exhibit MOCs there, they’ll wave your registration fee for the full three day event (yes, note that this is a “convention” but it only runs from Friday to Sunday).