+1 for a full day at CYB, if not more. I’ve done the Beast and the red squirelly one in one day, then some stuff over the road on another visit, would have made a great long day all in one go. Bike shop there for the ‘It was alright before I put it in the van’ tech problems of day one, good food, etc.
Got to be worth considering Snowdon for the ‘I’ve done it’ badge, although it’s not much actual riding. Ranger’s Path descent is something to remember.
And Antur Stiniog is just a great laugh. I’d do it in that order as well – big day first, then the techier descent on Snowdon second day, then the pure fun of Antur last day, as you’ll be right in the mood, plus anyone who wilts a bit can just stop getting in the uplift van and got for a cuppa/goof about on the pump track without disrupting the day.
Penmachno’s fun, but the one I’d least like to do again.