here is a list of stuff i my self find necessary though i don't have most of these ~_~
exterior :
21" style 215 wheels
shadow line
comfort access <<< a must
auto open/close for tailgate
interior :
comfort seats (vented and heated)
Logic 7 audio system <<< a must
USB interface
Backup cam and PDC <<< a must
full leather dash
mechanics :
active steering
adaptive drive
x6 50i
hope that helped