Carol, I'm not sure that much of the MB area wouldn't still disappoint you, in regards to non-commercial, natural, quiet areas for birding - especially in the summer when traffic could be pretty intense. That aside, the Marriott's immediate neighborhood is quite nice. If you're wanting closer access to the 2 parks, go south, to Garden City/ Murrell's Inlet area, which is quieter than MB proper.
Otherwise, what I've come to like about Myrtle Beach, where I often go off-season when there are no crowds, is the direct front view from an oceanfront balcony or chair, watching the pelicans and seagulls, coupled with the easy access to commercial stuff like Imax and films for rainy or cool days. It's really more of an almost-urban experience, with an oceanfront, for me. I was accustomed to much prettier natural beaches on NC's barrier islands, and at first MB was somewhat of a shock, until I settled into accepting it for what it is, and really enjoying the extra-beach activities. Many of my friends don't like it particularly, compared to other NC beaches. Most of the shows aren't my style, but we did go to Mediaeval Times once and had fun.
As long as you don't have expectations of wild, natural beaches without highrises and cranes, the construction kind that is, in your range of vision (aside from the parks), and don't expect tasteful, upscale-looking controlled development like HH, you can enjoy yourself. I haven't seen litter on the beaches themselves, and if you like shark's teeth, we found about 40 over New Year's, though they're not as plentiful as in years past.
Have you been to Duck NC? That town is very pretty, and has some great access to areas for birding, kayaking etc. Between the 2 destinations, it may be more to your taste.