Wynn is on the Strip, but like all the other mega resorts it located far back from the street.
I've stayed at the GN, it's the best hotel casino in Downtown, it is on par with ave to below avg strip properties think Flamingo or Ballys. Big notch down from the best places on the strip like Bellagio, Wynn, Venetian, and Caesars.
BlackHawkPaul is partially right there are some shity places downtown (DT), Golden Nugget is not one of them. The best part of DT is the low table limits, I'm a craps player and there are very few if any strip casinos I can afford to gamble. Also DT they have bands playing on different stages all summer in the street, a step up from suburban Chicago summer fests, not much of a step. It's free and the casinos open bars right out on the street, some with dancers. It is kind of low rent, but it is a party.
Bottom line GN is cheaper than strip properties but much nicer than other DT places. Plus if you want fancy stuff you can take a cab or a bus to the strip, it's not a prison.
One more thing, GN has a great pool called the Shark Tank. If you can afford it the cabanas are great.