I recently bought a Northwest 4 days in 8 Rover (£83.90) from Wigan. Based myself for 3 nights at The County Hotel, 400 yards from Carlisle Station. Double room en suite £95 for 3 nights. Had a great time. Stopped off at Carnforth on the way up. Lovely town and the Heritage Centre on the station is fabulous.
After checking in, caught the Cumbrian coast line to St Bees. Sun was out at low tide, so a fabulous early evening walk along the sandy beach. Both there and back I was pretty much the only passenger on the train.
Day 2, I bought an all day Stagecoach bus ticket for £11.50. Did Carlisle - Keswick 90 min journey, plus a few journeys on the open top buses around Derwentwater. Again, not many passengers, but Keswick itself was busy.
Day 3, I travelled to Settle on the Carlisle - Leeds line. Busy outwards, last return train was me and a couple of other passengers. After a pleasant walk from Stainforth Force, stopped off for a few pints at Settle Social Club, 2 mins from station. Friendly locals and a lovely club.
Day 4, I checked out and travelled south to meet a few friends in Ulverston. Visited the Laurel & Hardy Museum which was great and a walk around the bustling market town. Jumped on the train to Barrow, before returning to Wigan.
I still had one day rail vaildity, so the following week had another trip to Carnforth.
Great trip and thanks for all the recommendations on here, they were most appreciated.