If it weren't for the twins, I probably wouldn't have opted for another SUV (been driving them since 16). The X5 (with sport pack) stood out because it's got similar driveability as a regular sedan, but make no mistake - you can still feel the weight even with a 4.8 under the hood, especially if you're going to compare with sedans as you mentioned. The RR Sport was never a consideration for me because of reliability but I've come to find that BMW isn't exactly high up on that chart either. Despite it's faults, I still love the thing and would buy another before any other brands. When I'm driving other cars for any amount of time and come back to the X5, it feels rock solid on the road - can't beat it.

You have to decide if you'll have a lot of gear as it'll be a family car. It does the family thing very well and a 4.8 should satisfy you to an extent. Jack of all trades - if you're talking about snow - then absolutely. Mountainous terrain, I wouldn't try.

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'08 X5 3.0si - Alpine White / Saddle Brown interior
Specs: Sport Pkg, Premium Pkg, Tech Pkg, Comfort Access, Aero Kit, Style 433 staggered 20s on Conti DWS
Mods: Carbon 35 tint, LED angel eyes, GP Thunder 7500k fogs, H&R 20mm/25mm spacers, clear reflectors, gunsmoke-tinted taillights
Coded: Digital speedo, windows/sunroof/tailgate close via keyfob

X5 pics at Flickr