One more nice view I stumbled across when I was doing worm deed in Ram Duath. I've been in that very same spot many times (killing the drake matron and that rare black drake that randomly lands on that area) but haven't noticed this "window" cut right through the cliffside. Too bad my graphics settings have to be quite low at the moment ... I'm sure this view, overlooking Lehmä-Koti camp, looks a lot more spectacular in higher detail and environment settings.
"All of us with faces dour
waiting for the judgement hour"
There's an extremely good view from atop the mountain/hill right behind the quarry in Scary. It's the highest point in all of the Shire but not that many people know about it (it might even be a glitch that you can get up there).
Barring that, most of my favorite views have been mentioned--Evendim's Colossus, the Ridge-Racer spot in Eregion, Ost Barandor. But one I haven't seen mentioned yet is the view from above Esteldin. It's tricky to get up there, but possible.
I personally find the view from Amon Hen easily my favorite view in the game. I love how you can see the Anduin flow in the distance toward Gondor and the Mouths of Entwash in the distance.
.. and the Southernmost slopes of Amon Hen look towards Mordor as well. I've sat there above the falls trying to catch a glimpse of the glow of Orodruin against the cloud cover but nothing so far. When you're doing the epic part where you are re-experiencing the Fellowship's split on Amon Hen by all means ride a tad farther South and take it in.