My dad is 65 this year with over an acre to mow and refuses to get a riding mower. He has a couple of different sizes though from a commercial grade Scag with a 50' deck and a smaller 36' that's self propelled.
They have so many different sizes these days that you can still have a walk behind and it doesn't need to take all day to mow.
With a 50 foot deck, or even a 36 foot deck, Dad should be done in less than 5 minutes......