I think Gwyn is still pretty hard until you realize how many opportunities there are to parry him. He's really aggressive and can do some pretty big damage. Basically a taller, tougher unique Hollow rather than a boss fight that drags on for too long.
NG+ gets old because everything kills you in two hits and you kill everything in one or two hits. You'll probably realize all the weapons you missed or never got to make good use of and want to try using those on new characters.
And I'm pretty much over the whole Ornstein and Smough thing. This isn't a good boss fight. After being hit constantly by Ornstein's spear coming through Smough's knee, getting Smough to 10% health with just the Caestus and then being killed by Ornstein throwing a lightning bolt straight through Smough's pelvis, and also being killed by the invisible lightning residue from lightning buttstomp, I switched to Black Knight Sword +4 and just rolled right over them. Tired of these two. And the number of speedruns I've seen destroyed thanks to them.