For a different perspective on this question some listers may be interested
to read:
"As Art Museums Thrive, Their Directors Decamp" by Deborah Solomon, New
York Times, 2 August 1998.
As the article is rather long I won't include it here - for a copy see
Denis Dutton's posting "Looking for a job?" on the Australian Museum Forum
archive:
http://amol.phm.gov.au/AMF.archive/author.html#start