I'm quite interested in this thread, having only ever sat in 4 seaters I had never considered the seat height, but I had begun to notice the steering wheel is relatively low. So out comes the ruler ! My seats are around an inch higher than the sills, the spacers themselves are about 3" high. On the 4 seater there is probably no other option but to have the seat raised, otherwise rear passengers would have nowhere to put their feet. Incidentally, the distance from the scuttle to the top of the windscreen is 12". I guess the driving position is a little 'exposed', but on the other hand my wife hasn't moaned about not being able to see out, and entry and exit are probably a little bit easier...
Richard