OK...
This is interesting
But, let's keep it simple here... that is a little bit too much stats hands down, don't forget that we're trying to make a suggestion to a lady here, so we might keep our geekiness in check (yeah, mine too)
So to make the conclusion:
Galaxy S:
-pros:
faster chip
brighter Super AMOLED screen, bigger too
quite good camera (5Mpix + HD Recording)
Swype keyboard (why doesn't anyone mention this? It's the one of the few side of GS Software that is good)
-cons:
UI (as in Ugly Interface)
might take some time until froyo and bug fix to comes out (seems like it's really buggy, the GS forum is filled with complains)
no flash with camera
no dedicated cloud service
Desire:
-pros:
Better UI (that's really about sums it up)
Froyo is up already
flash for camera
-cons:
the chip is slower on Eclair, but on par with GS with froyo
basically the camera doesn't do HD recording, but froyo fixed it up
AMOLED screen doesn't have the same quality with Super AMOLED, and if you're one of the unlucky one to get the newest Desire, it came with Super LCD instead which even lowers the screen vibrancy a little bit (but it doesn't drains as much battery juice as AMOLED so there's plus and minus)
No swype (but you can get app to match)
No words yet on availability into HTCSence.com cloud service
So there you have it. Comparing Desire and Galaxy is is difficult because they have different fronts they want to show off. Galaxy got better hardware, but Desire have the best software and UI than most Smartphone currently existing.
For a woman, I'd recommend Desire though, as it's friendlier to use. Just ask someone to help you upgrade it into Froyo and you're done.