D3's don't float, they handle well
"Float" on a D3 with air suspension - sorry, but that's plain rubbish. If you drove the first one with the air suspension fully raised (at the off-road height) then that would certainly account for it, but you clearly didn't get above 50kmh which is the speed at which the air suspension will lower to normal level - in the interests of safety. The Terrain Response (TR) knob setting of "normal / on-road" will not affect the suspension height setting in the circumstances you describe, so if the suspension setting was at "off-road" height then that's probably what you test drove it in.
Perhaps when you drove the 2nd car you were looking for the same "fault"; it's human nature. Similar to when you hear an unusual engine noise on a new car and you focus on it, so you're sure it's getting worse!!
These cars work great on the road, I can honestly say that for a 2.7 Tonne vehicle they handle amazingly well and eat up twisty roads - cornering flat with no wallow.
I had a good look over the LC200 at the Perth 4x4 show last weekend as I'm due to change my car soon.
What put me off was the cramped interior, Toyota have squeezed massive leather "armchairs" in the front with a huge centre console, it made a big car seem small inside. It also seemed cramped in the rear (2nd row seats) with intrusive styling where the sides curve into the roof. The 3rd row seats take up most of the rear luggage space and tilt up & sideways like in a D2 (so there's progress for you), they too would not look out of place in a Harvey Norman furniture showroom, so even when out of the way they are enormous.
I'm not even going to comment on the LC200's exterior rear end styling, other than to say it's the single biggest reason I wouldn't be getting one.
In fairness, I do like the front end styling of it though and love the new V8 Diesel :D