If you ride the Beast (long) and the Tarw (not as long) trails I think you cover almost all of the trail sections. There is a fire road loop of pointlessness at the farthest point of the Beast, just after the forest cafe but you can avoid it if you study the map and are prepared to go up a steep road (that’s a lot shorter than the fire road loop of pointlessness).
So it depends on how fast as a group you are. If I was there with some mates in that time period I’d maybe go for the Tarw on Friday afternoon and the Beast on Saturday. Then on Sunday ride whichever trails you enjoyed the most. The MBR and Dragon’s Back trails are both subsets of the Beast and there are a few other small loops you can construct out of various trail sections too. For example it is very easy to stitch the initial and final parts of the Beast (Badger, Pinderosa, Beginning of the End, Glide and Seven Sisters, according to my map) into one small but fun loop.