Edinburgh – St Andrews is a very laid back friendly event, with all the money going to a good cause. It’s not difficult but also far enough (about 67 miles) that there’s still a challenge to it. I reckon I’ve done it 14 or 15 times and still enjoy it. Oh and the food stop at Freuchie is one of the best ever!!
While the Tour of East Lothian only has one real climb, it is a belter. And the weather can be grim. Not sure I’d recommend it as meeting the OP’s requirements. It can be one of those “we loved it because it was so horrible” events beloved of sports like cycling. That said my entry is in again for this year.
As someone said above, don’t be put off the idea of a sportive. They get all sorts of riders, from the ones wanting to do a fast time down to the ones just wanting to get round. Kinross is a very friendly event. Best thing about doing a sportive is coming on here, calling it a race then sitting back and waiting for the irate, furious “it’s not a race it’s a sportive” responses to come flooding in.
The Tour o’ the Borders might be worth a thought. Closed roads and you can decide between short and long routes when half way round. The short is definitely in the category of manageable (the Talla climb is brutal but one you’ll look back on and laugh). Folk do it on all sorts of bikes.
Just remember this is Scotland though and even the summer events can be wet, windy and cold.