Myrtle Beach IS touristy, but in a good way if you have small kids. There are two giant shopping/entertainment areas, Barefoot Landing and Boardwalk, that are great just to stroll around, get an ice cream, ride the amusement park rides, peek in stores, lots of photo opportunities. My 4-year old LOVED the "mirror maze" that we stumbled across. Alligator Adventures was awesome, really amazing.
I always thought I hated mini-golf but I got converted on this trip. There are dozens of courses and my kids went beserk -- one of them has a little "mine train" that takes you to the top of the course, another one has a dragon that breathes fire, etc., all very hokey compared to Disney but very cool compared to anywhere else. We played at four different courses in four days -- my 2-year old just ran around like a nut and threw balls in the bushes, while my 4-year old and my husband played for real.
Many of the hotels have lazy rivers and little waterparks. We barely went to the beach since the pools at the hotel were easier, no sand to deal with.
No question Myrtle Beach is the most touristy place I've ever seen, and I'm usually someone that prefers an outdoorsy, more natural vacation, but I really loved our trip and will definitely go back. The kids were just delirious the whole time with all the stuff to do and see.
Have fun!