Lucky for you I used to live there!!!
You MUST MUST MUST go to Broadway at the Beach for the shopping.
There are also some REALLY good restaurants there to eat at. Joe's Crab Shack, Liberty (MY FAVORITE), Tony Roma's (awesome ribs).
Across the street from Broadway on the backside of the property there is a water park and the Nascar Speedway.
Also be sure to take the little one's to Bullwinkle's one night for dinner. It is cafeteria style food but there is a huge play park inside there for them to play in..It is lots of fun!!!
LOTS AND LOTS of putt putt places, Ripley's aquarium, IMAX theater, go-carts etc.
Hotels : I don't recommend that you stay on the beach in MYRTLE . 1. you are going to pay lots of $$$$$$ even for a roach motel in June. Also the traffic up and down the main strip is CONSTANT, and you will have the hardest time coming and going. It is so loud your children will not be able to sleep at night. (I lived 3 blocks over and I could hear the noise at my apartment).
I suggest you either stay in N. Myrtle or possibly further down in Surfside, Garden City, Murrell's Inlet or even Pawley's Island (very nice place) (We stayed at the Hampton Inn in Pawley's last June and it was like 85.00 a night through Expedia with a great cont. breakfast)
Litchfield Beach is in Pawleys and it is in NO WAY as packed as Myrtle. Alot cleaner too. You can also go to the Myrtle Beach State Park which is more family oriented and not as packed.
Oh I envy you I love it there and would LOVE to move back there one day!!!
My DH and I admit that yes while it was always crowded there we miss it because there was ALWAYS something cool going on to do!!
Have FUN...have anymore questions PM me!!