Well, I'll give you the Prelude vs. S2000 portion.
The first thing you'll notice when you get in is that the S is obviously more of a cockpit design. Where the Prelude has some comfort and an adjustable wheel, the S has an adjustable seat and depending on your height there may only be one position for it.
Then of course there is the driving experience. As you know the Prelude is fwd and the S is rwd. With these specific cars I find a big difference in the 'push vs pull' feeling of the drive. Driving the Prelude hard still feels like it's being pulled around, which it is, where the S is very obviously being pushed by the rear. I only say this because there are some fwd and rwd cars that don't feel one way or the other extremely, but these two cars do.
I think the Prelude has good power and has a pretty smooth power band. The S has a much more powerful feel, especially up high, but the low end does suffer from a lack of torque. I know that there have been billions of posts all over creation about the shifting habits to eliminate the missing torque, but honestly, the lack will always be there. Now you may not notice it since you drive very similar cars, such as the Prelude and NSX, where the engines are somewhat similar. But if you've driven something from the BMW M series you'll know torque. If the S had the low end torque of the BMW M Coupe it would be the best all around roadster ever, IMO.
Then there is the 'reflex' of the car. The Prelude is a pretty responsive car. It accelerates well, turns as well as a fwd can be expected to, brakes well, and can provide a very nice drive. The S is all of these things multiplied many times over. The acceleration is much more severe especially in VTEC, and the handling aspects are much more precise. There is a lot less roll in the S on hard cornering than the Prelude, as one would expect. The S is just stiff, there is no better way to put it.
Now the things you used to enjoy about the Prelude, such as a back seat, and multiple cup holders, well, they are gone. There is a cup holder in the S but as you'll find out soon enough the location isn't desirable. You'll also miss the hardtop at some points due to road noise. I don't even notice it anymore, but when I get into my A4 it's nice and quiet. The Prelude came with a pretty good stock stereo system, the S did not. There will be a need for some speaker upgrades and some rear speakers in order to get close to the experience from the Prelude. The trunk is obviously smaller, but I can still fit my golf clubs in the S so I don't care. :smile:
Those are the basics, hope it helped....