Sounds like we do something of a mixture between you, OP, and chauffeur
Mine are 3 and 1. We get back from work/nursery nearer to 4.30, but we don't start bed time til more like 6.30.
Yes, much of the evening is cooking, tidying etc, but we often stop in the park on the way home, or I walk to nursery having dropped the car at home, and we walk / cycle home again.
The boys adore it if we get a blanket out, and eat tea in the garden (sandwiches usually), so can see picnicking out somewhere would be amazing for them.
Then, in this hot weather, we play in the garden rather than TV - water, chase, balls, bikes.
We don't tend to do too much, but we've all had a long day at nursery or work, so swimming or some of the other ideas above would be too much for me personally, but it depends on how close these things are, I guess!
Don't stress, mine are equally happy pottering with a bit of parental guidance, as an activity.