What kind of mileage on the car....

Sounds like you have worn piston rings, you have good compression because the oil leaking past the oil scraper ring, gives the compression rings a better opportunity to seal in the cylinder.

I just went through the same thing with my 300D, I was using 2 quarts every 500 miles. Valve seals won't cause that big of an oil consumption problem. Usually the valve seals only cause smoke at start-up because the oil actually has a chance to seep down past the seals when the engine is not running.

At best valve seals may cause a quart useage every 1000 to 1500 miles, if that.

Hope that helps a bit!