As others have said, it's physically impossible with a 2 channel system to have a sweet spot big enough for 2 people sitting normally. I would run a center channel when you have guests over or even for yourself on some music. This way you trade holographic (stereographic) imaging for pinpoint center, flat image. Soundstage can become overly grand but with the right music, the right mood, it's a fun time.
EQ/DSP will almost surely be necessary. Here I would ignore tonality problems and prioritize an even bass response across the sofa