"Shinjuku is defn the more "electronics" shopping area, I gather? I was
wondering, what are the dept. stores like in this area? I am wondering
if I can skip Shibuya and do Shinjuku instead... Tell me, how does
Ginza compare with Shinjuku?"

Shinjuku has some electronics and camera stores, but the main
electronics area is Akihabara, where store after store sells
electronics.

Ginza is the place for luxury shopping, but other than that there's no
reason to go there.

Shibuya has one ultra-luxury department store called Bunkamura, but the
rest of Shibuya is aimed at teenagers - record stores, Internet/manga
cafes, T-shirt stores...

Shinjuku has some huge department stores, which tend to be mid-range
rather than luxury.

" in Tokyo on W-Th-F... Friday night should be a good time to catch
Harajuku, right? Is Harajuku closer to Shibuya? The youth culture
sounds really fascinating too!"

Harajuku is pretty dead on friday night though...it's about a 20-minute
walk or 3-minute train ride from Shibuya. If you do want to try to see
the youth culture, the places to go are the 109 Building in Shibuya,
and the entrance to Yoyogi Park near Harajuku Station.