You could be seriously disappointed. I love GCH but I'm willing to pay the extra money for a little less walking. I don't find DtD especially busy even on weekend nights. The parks always seem much busier to me! DLH is wonderfully "Disney" themed and not that much more walking, especially if you utilize the monorail in DL to get back. Remember just because people walk right into GCH from DCA that doesn't mean their room is right there. You could be stuck down one of the insanely long halls. We were in Fantasy Tower at DLH with a room near the elevator and it was nice walking wise.
I just don't recommend GCH for people who are penny pinchers at heart and can't really shake that on vacation. Wondering your whole vacation if it was worth the extra $$$ is just no fun. Of note, GCH rooms are smaller than DLH & the theming has zero "Disney" feel for all practical purposes.
As I said, I love GCH. But I'm not an "active" person
so the proximity deserves the extra $$$ for me.