A great deal depends on the time of year, of course.
Here's the url for the local Audubon Society:
http://www.redrockaudubon.org/
Some notable localities:
For montane species, the Mount Charleston National Recreation Area. It's reached from US Hwy 95 via Nevada 157 (Kyle Canyon, and be sure to stop at the visitor center) and Nevada 156 (Lee Canyon; bristle cone pines grow by the roadhead.) The road goes from Hot Desert around 3000 feet to coniferous forest at ca 8000 feet, and the Charleston Pk loop trail continues to alpine tundra, though it's a brutal climb, starting at over 8000 feet and gaining almost 3000 feet in the first two miles.
The Red Rock National Conservation area is good for high desert birds, with good paved roads, developed trails and a very good visitor center for orientation (and regional bird manuals for sale.)
The Springs Preserve, near the strip, has drought tolerant plantings, remnant desert riparian habitat, and a major exhibit on regional environmental concerns. The gardens are free, but there is charge for the exhibits.
Sunset Park (SE corner of Eastern and Sunset) has an artifical lake that attracts large numbers of wintering water fowl that are VERY habituated to people. (Photographers may have to shoo them away in order to get the whole bird into a wide-angle lens.) There is also an area of preserved dune habitat that supports desert specialities.
The Henderson Bird Viewing Preserve (aka tertiary treatment ponds of the Henderson Wastewater Treatment Facility) has a visitor center where you can use their library of regional bird guides, view their humming bird feeders, and walk the trails around the ponds. Even in summer there are quite a number of breeding species of waterfowl and shorebirds, and the vegetation around the ponds supports a rich population of the local desert birds.
The Lake Mead National Recreation Area provides over 1,000,000 acres of desert habitat with well developed and marked access, graded by the type of vehicle needed, whether passenger car, high-clearance, or 4 wheel drive.
What kind of birds and habitat are you most interested in? There are lots of nearby localities: all the above are actually, or effectively, inside the metroplex city limits.
Will