on the wrist in my opinion because 1. The curved case allows the watch to fit very snug, thus it does not feel like it is sitting on top of your wrist. 2. As SJX reported, it is relatively thin. This plus #1 again makes it feel like it is a part of the wrist rather than sitting on top of the wrist. 3. As also stated the lugs are not very long. Watches with longer lugs always seem to make the watch feel bigger in my opinion.
A quick compare/contrast to another watch in my collection-- Fifty Fathoms-- This watch is 45mm but also has short lugs which helps make it fit comfortably and not appear too big on the wrist. In contrast to the Santos 100 the Fifty Fathoms in quite thick (15-16mm I believe) which makes it feel a bit clunky as it definitely sits on top of the wrist rather than fitting the contour of the wrist. Anyway, the Santos 100 is one of my favorite watches and it gets a lot of wrist time. I like wearing it to work because it is virtually scratch proof (ADLC model) so I don't worry about damaging it. Thanks for the report on all three models SJX.
Stewart