My father owned one and wore it often... of course, things were much more "formal" 20 years ago.
My husband does not own a tuxedo. In fact, I've never seen him in one. He owns several very nice suits and when we are invited to a "black tie optional" event, he wears his dark charcoal suit (almost black) with a crisp white shirt and a dark/conservative tie with cuff links and polished dress shoes. He's never been "under dressed" in that combination!
I would go with the suit unless you frequently attend very formal events. Otherwise, go for a classic well-cut suit with a very simple/elegant accessories. No colored shirts, no flashy or patterned ties, etc.
Where we live (NY) this would mean at minimum, cocktail attire but ladies are welcome to wear floor-length gowns. Where I grew up (in the South) this would just mean that you could opt out of wearing opera length gloves, but hems should touch the ground and men should be in dark colored evening wear.