Right, assuming its going to be a two day trip how about this for a draft schedule?
Day One.
Brownley Hill.
Round trip for those who want to dangle off ropes and so on.
For those who don't a look around the Wellgill Flats, workings on BH vein and the engine room if an electron ladder is taken for the short climb up.
Day Two
Rampgill.
Plenty of rises for the acrobatically inclined to clamber about in.
Plenty pretty things for any photographers.
Plenty of genuine IA type interest for everyone else.
As for accommodation, Cherry Tree Cottage in Nent is handy for the mines - £25 per person per night or perhaps a pub/B&B in Allendale Town where there's the choice of a couple more pubs and shops to stagger between on a night.
There's also the bunk house on site which will likely have no other visitors at that time of year but is a bit spartan.