not to be mean, but I'd stop worrying about rim size. Just worry about the tire size
I run 17"s with 35"s and they look fine. I've seen big ass trucks with 15" rims and border line monster truck tires and it looks fine. 18 is a great compromise between the big 20" rims and smaller like 17".
In my opinion 33's are small regardless once you start leveling and lifting. You really have to consider 35 or bigger. I like your idea of 4" and 35's.
I considered 4", but I know i'll get bored of it and wish I paid $50 for the 6" so i'm going straight to 6"