RIP. I liked him in both, his TNG appearance and his appearances in Three's Company as Chrissy's father.
I like what the novelverse has done with Offenhouse. First, he becomes the Federation ambassador to the Ferengi (a marriage made in Heaven, really, since nobody knows more about money than Offenhouse, and the Ferengi will certainly respect that), and later, Federation Secretary of Commerce.
I have a feeling those would be good reads. Richman had charisma and made for a great character actor for sure. He made the most impact, for me, as Reverend Snow from Three's Company... but he had stage presence; his presence was always instantly recognizable as character and not typecasting. Offenhouse was not a cookie stamp template of Reverend Snow!
Always felt bad for Mr Offenhouse- he planned ahead for his welfare and still lost it all anyway.....