I wouldn't put it under the armoire, just the sofa.

I would try it first with sofa front legs on it, but to be perfectly honest I am not that fussed over rugs having to run under the things around them. I think the perfect color and pattern of rug are far more important than size. Also realize that's a minority opinion of about one :-)

I also think it should be just partially under the sofa.

I forget where it was, maybe Apartment Therapy, that illustrated several "acceptable" ways to place area rugs in furniture groupings.

The simplest rules are "all on or all off", referring to front furniture legs. But they also showed examples that "broke the rules". AS long as there is a logic to it and it feels visually balanced, I think it is pretty much your call!

Here is a very good Houzz atitcle on the subject

[Area Rugs vis-a-vis Furniture[(https://www.houzz.com/magazine/11-area-rug-rules-and-how-to-break-them-stsetivw-vs~222609)

The rug came early and arrived today instead of Sunday. Wasn't sure about it at first. Online it looked more solid grey w/ a white pattern but IRL it has far more color variation amongst grey & browns. Unrolled it anyway to really get a feel of it. It's growing on me. It actually measures 6'7"x whatever so it def. floats between the armoire & sofa. On the long end it goes under the chair and under the other side of the sectional sofa. Think I like it! Will take pics soon to get your feedback.

Thank you! After 10yrs or so it's all starting to flow together from outside to in and from room to room. So glad I took off decorating for a yr or two and stopped obsessing!

Can't wait to see it!