At the risk of causing a riot, the current writer must confess that she's only once eaten from In-N-Out Burger and couldn't figure out what all the fuss was about. Then again, I'm not into fast food and this burger had been driven across town and may have suffered in transit.
For those who don't know, In-N-Out Burger is a southwestern phenomenon -- a pioneer of the drive-thru concept that's known for its cleanliness and fresh ingredients. It was recently the top "fast food" pick of a number of Las Vegas' notable chefs (see Today's News 9/12/2009).
In terms of any of the Las Vegas venues being walkable from the Strip, we'd have to say no, although that depends on where you're staying and how much you like to walk. The In-N-Out on Dean Martin Dr. (formely Industrial Rd.) is at the corner of W. Tropicana Ave. and while it looks pretty close to New York-New York, it's not a walk that we'd recommend, since W. Trop is in very busy multi-lane mode as it approaches the Strip, with traffic vying to get to/from the airport and the Strip and on/off the freeway.
If you're staying further north on the Strip, there's another In-N-Out at 2900 W. Sahara Ave. That one's definitely walkable from Palace Station but a bit of a hike from the Sahara and again, it's not really advisable nor likely to br an enjoyable walk, both because of the busy traffic getting onto/off the I15 and the fact that it's a pretty steep uphill incline on the way.
If you're determined to try In-N-Out and definitely won't have your own wheels, you could spring for a cab which, according to www.taxiwiz.com, from the Sahara would cost you approximately $8 one way ($6.81 plus 15% tip). The same theoretical fare holds true starting from the MGM Grand and heading for the In-N-Out on Dean Martin Drive. Alternatively, here's a link to the schedule for the 201 CAT bus, which services Tropicana Ave. and the 204 route, which covers Sahara Ave. Finally, here's a link to the In-N-Out map, which covers all of their locations, just in case you happen to find yourself wandering further off the Strip and happen to be in the vicinity of one of their other locations.