lol, we have a group from Chicago going to myrtle over those same dates.
We played river club a few years ago and I remember some pretty long holes and lots of water, I think all but a couple holes had water in play. Good risk- reward course, lots of room off the tee but then 2nd shot makes you think. The greens were ok, a nice course.
I didn't go the year they played traditions but I hear it is very nice.
World Tour is awesome, they assign a guy to your group too that stays with you all day and provides good insight on club selection etc. The 1st and 18th on the "open course" are modeled after St. Andrews and are just hilariously wide open with shared fairway, so its total grip it and rip it and long drive contest etc. Also the beer comes in glass bottles, carts are like state of the art, the whole experience is top notch, well worth it.
We're also staying at River Oaks which isn't a bad place, we get a couple places off one of the fairways, at twilight/end of day you could just walk out the back deck and start taking practice shots, no one around. If you're playing poker you should talk to the shot girls at the Masters, they're much crazier and party harder (and cheaper) than the actual dancers. We had a couple come to the room to deal and serve drinks and things got pretty wild. We also got them out on the course the next day, the Witch let us bring them out (skinned the starter $50 and he gave it back to us, he said no prob), they were wearing some skimpy little golf outfits, quite fun, the group behind us was from england and were loving it. The pro drove bye and was pretty cool about it, he said keep pace and he had no problems.
Myrtle is just awesome though, I hear you about the "misfortune" part of organizing for a big group but once you're down there its just a riot.
Also, aerification schedules come out in March so its good to check those and then adjust/change tee times and courses according to that.
http://www.ezam.net/myrtlebeach