Just make sure you all agree on exactly what you mean by your waiting place.
I know of people who waited 'in front' of the turnstiles (which to them meant inside the park, in front of the turnstiles after they entered) for people who were also waiting 'in front' of the turnstiles (which to them meant , the turnstiles should be on front of them, ready to enter).
I have also waited for my DH 'in front' of Spaceship Earth when we were both on different 'fronts'.
Cell phones are also helpful in hooking back up.
Also, if you are staying at one of the WDW resorts, you might want to consider using WDW transportation. Especially, if you are going to MK - when you park, you still have to take the boat or monorail to get to the park turnstiles. The bus drops you off right by the turnstiles.