I'm up for a trip.
A couple of places I'd like to see some time are Croesor (or is the long walk too much for an evening?) and Llaneilian (not much underground).
Or if you fancy something completely different but still cold, wet and cramped, I haven't had my kayak in the water yet this year. I have a second spare one so there's the option of taking it in turns to walk or kayak or just splashing around depending on numbers, weather, etc.
"The true crimefighter always carries everything he needs in his utility belt, Robin"