Well, you have picked one of
THE hardest instruments to record. I have a Boston 7'-2" Semi Concert Grand Piano that I record. Incidentally, there are numerous threads on this board about micing a piano. Do a search for some really great techniques.
I use 3 mics to record mine in this way:
Mics: 2 Neumann TLM 103's.
1 Shure SM 81
I place one of the TLM's about 6" above the bass strings and about 18" back from the pin block. The other TLM I place Above the treble strings approx. 2/3 of the way down the pin block. I situate it about 4" above the strings, and about 12" behind the pin block.
The Shure SM 81 I place at the tail of the grand, just above the rim. (Seems to catch some of the nuances and over tones.)
This technique seems to work really well for
Classical Music.
Here's an example of a recording done using this technique:
http://artists2.iuma.com/site-bin/streammp3.m3u?190193
Other techniques may be more appropriate for other styles of music. For instance; I really don't want any hammer noise. It just doesn't seem appropriate for classical music. However; hammer noise may be desireable for rock or jazz styles.
Experiment, try a multitude of different techniques, keep a really good log sheet and write done what you did for each set-up, and find a ttechnique that works for you.