Bike ride, picnic, then ride home.
Local parks
Library trips (they have a scheme here where you read 6 books over 6 weeks and get a medal at the end, you have to talk about the books when you return them but stickers/activities every visit)
Making a tent/den in the garden
Buy tennis racquets and balls, then spend time in the park
Hiking - Liebling was able to go for a 6km hike from age 5, with snacks and drinks on the way and the promise of a bus ride home at the end
Go to the beach, pick up some stones, and paint them at home
Paper mache models (I detest this option, but you may not)
Heritage days out - OK they cost, but going around old buildings with mediaeval fighting displays keeps most people happy
Late night double-feature movies - do this at home, home-made popcorn etc - then get a lie-in the next day, double bonus

Of course, the usual board games, hide and seek, reading, writing short stories, problem solving and jigsaws also get used a lot.