After a few failed attempts I finally built a bike that my dad finds comfortable. It's basically a flat bar hybrid but with tall riser bars for a very upright riding position.

He hasn't ridden a bike regularly in decades, if ever. He weighs about 260lbs and is trying to get into better shape. The only sticking point now is the saddle. I'm sure things will get better the more he rides, but I remember when I first started biking that different saddles felt very different to me. Now I can ride pretty much anything including hard, narrow racing saddles.

So, any specific recommendations? He doesn't want a Brooks, since the amount of miles required to break it in will likely take him a year or two to put on. He just wants something that is comfortable.