Is three nights (2.5 days) enough time to see the major sites in Moscow?

We will be coming from St. Petersburg, where we will be for five nights (our second time there) and thought I should see Moscow while my visa is still good.

Kremlin, Red Square, Pushkin Museum, the Arbat seem like the most compelling sites based on my reading so far. I'm guessing those would take two full days, leaving a half day for other stuff.

Enough time? Any other compelling sites? (GUM, Gorky Park, don't seem to be compelling enough to stay a fourth night.) I figure checking out a couple of major streets or pedestrian areas would be a good fit.

Thanks in advance!