Mine's got a lid on top, that I raise. Put two mics 2' apart or so, preferably condensers. I've used U87's,
KM84's, AKG Bluelines, but my favorites were (and are) a pair of Mictrotech Gefell UM70's in cardiod.
Then put your best ribbon mic (I use a BK11, but recently tried a Stephen Sank modified B&O with a 44BX ribbon in it with fabulous results) in the "sweet spot" in the back of the piano, wherever that might be. On my piano, it's in between the 2nd and 3rd large ribs on the treble side.
Check for phase before pushing "record", and blend to taste.
I've used nothing but the BK11 on lots of mixes, but they were not mixes that had predominantly piano, like you're trying to do...
Luck!
PS...what mics do you have?