Would Maris be a good spin-off? We have never really seen her. I mean it could work. What do you guys think?

Hmmmm, i don't know.
I dont think you could find an actress that could live up to the reputaion that Maris has been given.
For years, the characters of Frasier have told us about this person that is so wierd, insuffearble and downright crazy that it would be nearly impossible for some actress to bring this character to life.
Plus, I think actually seeing Maris kind of ruins the gag.
Other shows have revealed thier "invisible characters" and it has always been a letdown.
This is a bad example, because it was a lame show, but on Suddenly Susan, Judd Nelson's character always talked about his annoying wife he was trying to get rid of, telling us story after story about how evil she was, and when they finally added her to the cast, she didn't live up to the "hype" her character had been given. It was more fun to imagine the character.

The writers of Frasier are some of the best on TV, but I don't think that they could pull off such a feat.

I think the closest thing you'll get to seeing Maris already happened! They made Nile's ex wife Mel a close comparison. Maris wasn't exactly written as a likeable character. Even though the Frasier writers can do magic transforming characters from heels to lovable rubes, I agree that Maris is better off unseen. Just like Vera was on Cheers.

You saw Veras whole body except her pie covered face on the thanksgiving cheers episode. She wasn't obece or anything...she seemed average and she dressed nice

I believe Norm's real life wife was like this former super model. I remember when everybody was speculating on the finale of Cheers ( Bill Clinton appearing, Sam and Diane getting married, etc.) One rumor I recall was Norm's real life wife was going to be revealed as Vera. Supposedly, she's beautiful!