Myrtle Beach has lot's of fun places to visit. Broadway at the Beach is a popular entertainment area for tourists, there are over 100 stores, restaurants and nightclubs. Planet Hollywood and Hardrock Cafe are fun places to eat and they're both near Broadway at the Beach. A similar place is Barefoot Landing, lot's of restaurants, unique stores and a boardwalk that goes over a lake. Alligator Adventure is located at Barefoot Landing, it's a big reptile zoo and you can see alligator's and other reptiles and birds there so make sure you bring a camera if you plan on visiting.
House of Blues and the Alabama Theatre are located at Barefoot Landing. If you like outlet centers, Tanger Outlet's is located on Highway 501.
http://www.broadwayatthebeach.com
http://barefootlanding.com
http://www.tangeroutlet.com/myrtlebeach17
Hard Rock Park is a new rock n' roll theme park owned by Hard Rock Cafe. The grand opening was just a few days ago, so if you decide to go it might be very busy, but it's certainly worth it.
http://www.hardrockpark.com/index2.php
Ripley's aquarim is located at Broadway at the Beach. Tickets cost $18.99 for adults.
http://www.ripleysaquarium.com
Live entertainment shows (I've provided the links so you can find the prices, directions, etc on the website):
Medival Times dinner show
http://www.medievaltimes.com/Locations/Myrtle-Beach-Castle.aspx
Dolly Parton's Dixie Stampede
http://www.dixiestampede.com/myrtlebeach.php
The Alabama Theatre
http://www.alabama-theatre.com
The Carolina Opry
http://www.thecarolinaopry.com
The Palace Theatre
http://www.palacetheatremyrtlebeach.com
Legends in Concert
http://www.legendsinconcert.com
Other attractions you might like are, Myrtle Beach Waves Water Park, NASCAR Speed park, minigolf, the piers and boardwalks, fishing and of course, the beach. One hour north is the U.S.S. Battleship North Carolina in Wilmington, NC which is open to the public, so if you feel like a day trip, it's about 1 hour north and it's a nice place to visit.
There will be several places having fireworks on July 4th. There will be fireworks at Broadway at the Beach, Barefoot landing and the Myrtle Beach Chamber of Commerce will have fireworks over the beach. North Myrtle Beach is about 30 minutes from Myrtle Beach (where most of the attractions are located).
For more info on attractions in Myrtle Beach:
http://www.myrtlebeachinfo.com
Enjoy your trip =)