Like other sportscars billed as 2+2s, the Jaguar XK's effectively a two-seater; those rear seats are token gestures tossed at practicality more than at real passengers.
In front, there's no lack of space or accoutrements. The XK has expansive leg room and impressive space in most directions; it's roomier than almost all its direct, high-rolling competitors, though the Maserati GranTurismo and the newest 911 come close. The head room is better than in past XKs, and both the convertible and the coupe have seats with long tracks that allow lots of travel, and an adjustable bottom cushion. Coupled with a tilt/telescoping steering wheel, it's simple to find a sweet spot for driving. Touring and XKR-S models have standard heated front seat, while Portfolio cars have ventilated seats.
And then there's the back seat, which we've used more often for gym bags than for adults or even small kids. A couple of soft-sided bags will fit, but no one over 5' 5" will, even if they're soft-sided, too. The seats are narrow, and knee room is almost nonexistent. The same is true for elbow and hip room, since the teensy buckets are split by the drivetrain tunnel.
Trunk space is just as thin. On coupes, at least the 11 cubic feet of locked space will hold a couple of pieces of luggage. Convertibles lose 2 cubic feet and the opening gets even smaller. The high cargo floor, low-slung glass and stubby decklid make for a gorgeous rear end, but make little room for hard-sided suitcases.
Fashion exacts its own price, so while you're shipping ahead a week's worth of clothes, plan on soothing yourself in the XK's fabulously paneled and detailed cabin. The XK is crammed with glossy, deeply grained wood trim of a few choice grains, or aluminum trim if you like. The leather's stitched superbly, the carpeting is plush and thick. Cars twice as expensive aren't finished half as nicely as the XK, and its cockpit is worth the price of entry alone.