06 CLK350 Aftermarket NAV Recommendation?

Ok so I just purchased a 2006 Mercedes CLK350.  The car is not at the house yet but is on the way.  We are looking at wanting to get GPS/NAV with XM radio and iPod integration and was wondering what the best option out there was for it.  I just wish it would of came with it in the first place.  Is the unit space a standard doubne DIN, it looks pretty large?  Would a double DIN unit fit pretty easy?  I want something installed but dont want to have to have someone get all crazy with an install when something may fit right in and be the best route to go.  I was looking at the  Kenwood DNX5120.  It is a double DIN unit.  My wife of course is wanting something installed this weekend but I am wanting to wait and do a bit of research before taking the plung.  Also would you recommend having Car Toys do the install?  We are in the Denver area.  Thanks