Many many sights in WoW. Examples are stepping into Terokkar Forest and Zangarmarsh for the first time, walking to the top of that broken world tree in Grizzly Hills and watch the view, watching Azeroth from Black Temple, simply walking through Elwynn Forest, entering Dalaran Silvermoon City, Stormwind, Exodar....well any major city really for the first time and obviously the Wrathgate cinematic. I could on with that for a while. Also complimented with an amazing soundtrack, wich also sets an absolutely superb atmosphere.
The whole of Metroid Prime 1 and 2 impressed me non-stop. Beautifull scenery complimented with amazing music, it really sets an awesome atmosphere.
The GTA4-version of Times Square by night. Cruised by and I was réally impressed. Ofcourse the next thing I did was break in an expensive car dealer, and cruise through it again with some better set of wheels ;-)
Stepping out Oblivion's sewers.
Stepping out Fallout 3's Vault 101. More so then Oblivion to be honest, Oblivion on the 360 looks a bit meeh, still don't know why I bought it for the 360...
Landing on Halo for the first time in Halo.
The view from the highest point in Jerusalem in Assassin's Creed. Found the game incrédibly meeh, but that was beautifull.
BioShock's intro cinematic, e.a seeing Rapture popping up behind those rocks on the first time, complemented with that eery-ish tune, made my skin crawl with that feeling of lost glory and decay. Truly amazing, beautifull in it's own disturbing way.
Dozens of sights in Half Life 2. From entering Ravenholm, although that wasn't really beautifull, untill the Lost Coast level. Some awesome sights, some beautifull sights, but all great.
LOTRO's Shire, or the dwarven city or one particular vista in the elvish/dwarfish starter area where I looked over an elvish village, secluded between hills and water. It's a shame I didn't visit Rivendell, I can only imagine...
Guess that's all really, not even included all the non-beautifull, but awesome, 'wow!' moments. Then the list would be almost endless.