Most airports are set up with designated and well marked 'arrivals' and 'departures' sections. Tell your folks to just follow the large overhead signs for arrivals. They will likely end up near the baggage claim area that Prism99 suggests. Unless you all agree that they are meeting you at your arrival GATE (the area in the airport where you get off the plane), there should be no need for them to even park! In addition to the arrival/departure signs, there are generally large signs with specific airlines noted so you can 'pull off' to those specific airline baggage areas. They can truly just pull up outside your airline's baggage claim area.
All that said, sometimes if it's a really busy airport the picking up folks might get prodded along if they are hanging out near the baggage area for an extended period. Then they can just do a loop around the airport following the same signs. At Phila. airport - obviously a busy one - has a 'cell phone waiting lot'. I'm sure most major airports have the same situation these days. Those folks doing the pick ups wait in that lot until the arriving person gets off the plane and is headed to baggage claim. By the time those folks have left that lot, the arriving passenger has likely gotten their luggage and is ready to be picked up by the time the drivers get from the lot to the baggage area.
Enjoy your trip and the time with your folks. You'll have a great time. Just follow the herd.