I cannot imagine anyone favoring a Yamaha grand when given the choice of something else. But, they are really common. Their uprights have great bass for uprights... but their grands suck, IMNSHO. Maybe I have just had bad luck with them, but I have never found a Yamaha grand I really like. We have one at my church that I play occasionally. Action just feels wrong. I have no way to really describe it. Also, that thing can't keep in tune for very long. I have encountered similar problems with other Yamahas as well. (I play piano in jazz band. Lots of festivals have Yamahas.)
I think she probably plays Yamahas in concert because lugging around a grand from town to town is difficult. And Yamahas are everywhere.
Elton John may prefer his Yamaha CFIIS to anything else, but I still think he's crazy. :wink:
I do know that Vanessa really dug the pianos in Duets. Looked like Model D's or B's (C doesn't come in Walnut, if I remember correctly). Baldwin also makes some great pianos. As posted above, she has a Mason & Hamlin at her home.