I would concur with the opinion that a jaunt off into the Pennines (not literally) is worth the effort. Great scenery, especially over towards the 'wrong' side near the Lancs border and Ribblesdale. Useful experience too as nav can be a lot more difficult over the Pennines below 4000' than you may be used to up the Vale of York and round about, as there are considerably less recognisable ground features. It's easy once you get a feel for the place though.
Further afield, take a trip up to Carlisle either via the dales and the eastern edge of the Lakes, or up to Tyneside and down the Tyne valley. Again, the scenery alone is well worth the effort.