Thanks for the info. I wasn't really sure what was left in Poland. Greg's book mentions them, but not what ultimately happened to them.
In the notes section of the relevant chapter of "Court of the last Tsar" there is a summary of the fate of each palace. I think the chapter is called "Country Estates".
Greg and I later expanded the information he published in "Court of the last Tsar" by writing two articles for Royalty Digest Quarterly, if you are interested in finding out more. One of these appeared in issue 2, 2006, and is about Spala and Bialowieza, so you can read much more about the early history of these places and how Alexander III in particular used them (as well as the material on Nicholas, which is also fuller than there was room for in the court book). The information about their fate is also expanded on, especially Bialowieza.
The second article appeared in issue 4, 2006, and covers the Warsaw palaces: Skierniewice, Warsaw Castle and Lazienki. The main characters in these tales are Konstantin Pavlovich, Nicholas I, Konstantin Nikolaevich and, again, Nicholas II - with more about Skierniewice than there was space for in the court book.
THEN, we also put the Bialowieza stuff up on the internet, in the article on Directarticle, which is linked from this thread in several places. The purpose of that was to show the photos we have and lay out a ground-plan of the palace and estate. The text is largely the same as in the RDQ article, but rearranged a bit.
The best photos of Spala and Skierniewice are Violetta's photos on this forum.
Greg and I both like Bialowieza the best as a building, and regret its destruction the most. The estate, as Violetta says, is well worth a visit: it has a magical atmosphere. These days I think you can even stay in (next to) the old imperial station: - http://www.restauracjacarska.pl/
Not my cup of tea, all those pictures of Nicholas looking down, but I know some people would love it - so whatever floats your boat! :-) The apartments themselves look wonderful.