Hi Lectio,
Can't help you out on the driving experience (sad enough, haven't driven any Ferrari yet!) but you also asked about styling.
I believe the 355 is beautiful anytime I see it. The first time I saw a 360 Modena, I was a bit dissappointed by its appearence. The front looked too much Porsche to me! When you see the car more frequently it starts to attrack to you. I must admit I like a yellow 360 Modena a lot. However the 360 Modena looks better in very bright colors. I do not like it that much in the more 'reserved' colors like black or dark blue.
The spider is a whole different story! I fell in love with that car the first time I saw it. I really like the looks of it from aside. Although I would prefer a non-red color in general.
My personal opinion on looks is that they both are nice 'head turners' but the 355 looks more classic (which I think is a good thing!) no matter what the color of the car is. The Modena is just a modern car (nice looks too, but different) and I think is more Porsche like so not that distinct anymore. Depending on the color I like it or I like it a lot.
In other words: a 355 is no doubt a Ferrari for the public, and I think a 360 can easily been mistaken by a Porsche. Not that a Porsche is ugly, but I would prefer the looks of a 355.
Just my 2 cents.
Niels