Just jumping into some detail on this:
Can I assume the route should be under an hour to complete accounting for a moderate pace, say up to 20kms/hr?
Route is best to be uniform throughout, sealed where possible with no techie bits?
Avoiding major roads, or road crossings, perhaps capitalizing on linked shared paths?
A start/finish point in a park or off/road location with water fill up & dunnys?
Just a bike & a place to ride.