If you want to see the fireworks...
If you're anywhere on or near the Strip, it will be hard to miss the show as the fireworks go off at midnight. But some places have better views than others.
Avoid the madness of the Strip by heading to the Palms where Ghostbar will offer a view of the action from its outdoor patio on the 55th floor. General admission is $100 and a hosted bar is $200 10pm-1am. The Hard Rock Cafe Las Vegas Strip is a good alternative with open bar, food stations, and Champagne toast for $175. Then there’s the The Skyfall Lounge at Delano, which offers an impressive view of all the action from the south end of the Strip at 64 stories high. General admission is $195 in advance and a few grand if you want to reserve tables on the patio. The highest view, however is at the 1,149ft tall Stratosphere. There are a few different options available but the "Party in the Stars" is a pretty good value -- including three hour open bar, martini luge, food stations, and after-party -- on the observation deck for $250.
Even if you stay on the ground, you'll get a good show and an awesome party. New York-New York will host a Bridge Bash in the shadow of its replica Brooklyn Bridge with DJs, an open bar 8pm-midnight, and a spot on the Strip all to yourself for $135... Gilley's at Treasure Island will throw a party ($119.95) with an open bar 9pm-midnight and $5 mechanical bull rides. Order some barbecue while you're at it.
For the first time ever, the Las Vegas Monorail will turn one of its stations into a New Year's Eve party. The Third Rail Lounge will open in front of the Convention Center 8pm-1am. For $175 per person (or $300 per couple) you'll get unlimited food and drink with an elevated view from floor-to-ceiling windows. Even better, the price of admission includes free rides on the monorail all night.