Buy the Ultra. 

If you really don’t like it once you’ve listened a bit, return it within 30 days for a refund. 

I actually would hold off a bit, and wait for reviews to come in, on getting an Arc Ultra.  It also might make more sense to get a Beam Gen 2 and sub mini instead of an Arc Ultra.

As far as option number #2, I think you mean buying a Samsung home theatre package that includes sub and surrounds?  You can’t mix Samsung speakers with Sonos, if that’s what you’re thinking.  Anyway, I can’t speak to whether the Samsung is a good deal, probably best to check with a general AV forum for that question, but I would say the Sonos is the better option if you intend to build a better system, maybe eventually a whole home setup, over time.

Get the ultra

Then add to it when the wife isn’t looking