The Markers
In terms of markers, Clark County rates as one of the best counties for conquering! Unfortunately, the county is also home to more MIA's than any other part of the state, all due to urbanization that has taken place over the past twenty years. The good news is you won't have to be solely stuck within the boundaries of Vegas to conquer Clark's markers. Expect this as a general rule: less than half of Clark's markers are within the city limits vastly spread out across the Mojave Desert. In other words, game on! Prepare to kick back and let the Creosote tag along while cruising Clark's fast-paced highways. However, don't expect to conquer the county in one day. Although you can conquer the markers in two days, three days is a a much wiser plan and ideally, a full week if you want to enjoy yourself. A full week's time will allow you to split the county up into parts, visit a few parks and see other things of interest at the same time. For my own convenience in conquering these markers, I split Clark into three individual regions. You might find this helpful as well in your journey.

1) "The Mainland", might take you the longest to conquer. "The Mainland" is the county comprising everything north of Lake Mead. This includes the I-15 corridor, a few spur markers (such as #102 in Goodsprings), the SR 160 corridor and the highlight of your trip -- the two markers within Valley of Fire State Park!
2) The Cities of Las Vegas and Henderson themselves make up their own region. I took a full day to tackle these obnoxious markers accounting for traffic, breaks and pit stops. Even though Las Vegas and Henderson are not terribly difficult to navigate, the markers' distribution make conquering the cities a challenge. Expect a few instances where you're forced to double-back, especially if you wish to scout out any of the MIAs for yourself.
3) "The Needle" is the actual "point" of Nevada that extends south from the cities along US 95. This is an enjoyable drive, but prepare to drive it twice. There is no alternate return route back to Las Vegas unless you want to come back through California or Arizona. "The Needle" holds a few MIA's and some of Clark's more interesting markers, including a few superlatives!

In case you wonder about such things, I did pay careful attention conquering each area before moving onto the next to conserve my gas mileage. In three days, I spent forty dollars in gas with Clark's average price in March of 2009 at $1.99/gallon! Make your own gameplan, and however way you choose to tackle this piece of Nevada, may your views be wide and your stories be true. Just remember, what happens in Vegas is thanks to the North.