The Volvo XC90 is quite dated at this point, and one for under $15,000 might not be reliable. A new one is finally coming for the 2015 model year, but it'll be a lot more money.
The XC60 is newer, but probably not yet available used for $15,000.
2008 luxury brand crossovers available for $15,000 include:
Lincoln MKX - not outstanding in any way, but fairly reliable and owners seem to like them.
Infinti EX - nice performance, handling, and interior, but cramped interior
Acura RDX - sporty, but some people dislike the laggy turbo engine and/or find the ride overly firm
And not many of these are available for $15,000, so you might have to travel a bit.