We used to go to the SEC Picnic for my stepdad's work - LOTS of employees and kids so it was always held at a huge park.
Egg & spoon races, sack races - 3 legged race.
Santa came of course with presents for each age group.

They had activties stations (drawing, painting etc), face paints & at some of them they had proper rides but that was because it was a HUGE company.

Depending on your age group you could look at possibly a play centre, any local wildlife parks or adventure parks?