Ttodd, are your vents on the floor near the wall? If so I used to put bricks behind the legs of my sofa's to keep them from covering the vents. Granted I had a skirted couch then. I've also used diverters.

No, that doesn not seem like nearly enough clearance to allow the air to circulate in the room.

My sectional sofa blocks one of the air vents completely, also about 2" clearance. I have no choice. Our heat is heat pump air, which is cool, so this has not been a problem as far as the temp of the air. I also put a disposable air filter in the vent to catch some of the dirty air. We also have an electrostatic furnace filter.
I would be concerned if your furnace heat is hot air during the winter - that the heat from the air would prematurely wear out the fabric.

Would these work to solve your problem? I have one in my MB (we have a heat pump) under a chest which has worked great for us, both with a/c and heat. The temperature has remained the same with/without the deflector.

Here is a link that might be useful: Heat Register Defector

Oops, make that deflector! not defector! :)

THANK YOU ALL SOOOOOOO VERY MUCH!!!!!! I am so relieved & feel like my options have been opened greatly.

We have dual zoned heat pumps & central air so hot air is not blowing out. That was a really good point & one that I'd not thought of. The vent is in the floor close to the wall. It's an old, old house so as anyone w/ old homes knows: small rms., lots of doors to each rm. & windows everywhere. Add a modern heat system w/ flr. vents & you can get super limited w/ furniture placement.