I dived Myrtle Beach about 2 years ago. I went with Express Watersports
Express Water Sports - Myrtle Beach Scuba, Parasail, Kayak & dolphin watch & Ocean Sightseeing, Banana Boat And jet skis in Myrtle Beach South Carolina - Myrtle beach scuba Dive and highly recommend them.
I dived the Bill Perry, Tugboat/Airplane, and Goldfinch Reef. I can't comment on the suitability of the other sites you mentioned, but I felt that all of these wrecks would be suitable for newer divers, in good conditions. We had about 20 ft. viz on Bill Perry, 30 ft. viz on Tugboat, and 5 ft. viz on Goldfinch. Of those 3, I felt the Tugboat was the easiest of the 3 to dive. The dive op also had students on the Perry and Tugboat dives, so that should give you an indication.
The good thing about wrecks is that as long as you stay on the wreck, you pretty much can't get lost and can always see something. Stay within your maximum depth for your certification level and dive within your own personal limits.
Whatever Op you decide to go with, I would make these recommendations:
1. Take a scuba review course to freshen up your skills if you've been out of the water for several months or dive less than 10 dives a year.
2. Be up front with the dive operation when booking and with the crew when boarding the boat in reference to your dive experience and comfort level.
3. Rent the services of a divemaster guide if you feel you need it, or at least ask to buddy with a DM or more experienced diver.
4. Book your dives early in your trip. Weather conditions change and one of my dive days got scrubbed when I was there. Planning to dive earlier in the week will allow for make up days later if needed.
5. In reference to the sites, nothing is certain except for the depths. Temperatures, currents, and visibility change. The posted viz is the normal range, but I experienced below average viz during my dives.
6. Don't be afraid to not dive or to end the dive if anything does not feel right to you.
7. Book early. Summer is the busy season and boats fill up fast.
8. If you are even remotely prone to motion sickness-take whatever remedy works for you. On each of the dives I did, 4-5 people got sick. I came close one day and I've never been seasick ever. For me, snacking on cookies or chips on the way out seemed to work well.
Have fun and post a trip report when you get back. Feel free to post or PM me if you have other questions or want more info.