I didn't realize it, but Las Vegas has a really weird situation - all of the "Big 5" digitals, i.e. ABC, CBS, NBC, FOX, and PBS, are VHF!
You have:
ABC, channel 12, 119 degrees, 16kW erp,
CBS, channel 7, 119 degrees, 30.1kW erp,
PBS, channel 11, 61 degrees, 105kW erp,
NBC, channel 2, 60 degrees, 27.7kW erp, and
FOX, channel 9, 66 degrees, 86kW erp.
Note that these are transmit channels, not "virtual" channels.
So, it looks like what you really need is a good VHF/UHF antenna. The UHF would only be used for the "minor" digitals and the analog UHF's. It doesn't have to be really big, since you're so close to the towers. I don't know what kind of roof you have, but you MAY be able to put it in your attic - that's where mine is.
If these 5 channels are what you are primarily interested in, you can probably find a "sweet spot," rotation-wise, that will give you a solid digital signal from all. Somewhere in the middle of the 119/60 degree area would be a good starting point. Since they're all VHF, you WILL be subject to interference from electrical sources inside and outside your house and/or low-flying aircraft reflections. Not knowing anything about where your house is, I can't guarantee success, but if you buy the antenna from a reputable dealer, they'll take it back if it doesn't work.
Use a good quality RG-6 cable to run from the antenna to the receiver, and be sure to use a ground block if your antenna is outdoors.
Best of luck, and trust me, if you can get a good OTA signal, HDTV doesn't get any better!
Brad