I’d say North Wales or Lakes. The Yorkshire peaks just don’t have a proper mountain feel to me (despite meeting the official criteria).
You don’t say how old the lad is, or what you mean by an escape route, but I’d suggest heading to Cwm Idwal and then having a go at either Glyder Fawr or Y Garn.
Moel Hebog might be worth a look too. I remember that being quite straightforward and awesome views.
My hillwalking heyday was 20 years ago, but I started on Tryfan (perhaps a bit technical) and used to love the loop taking in Glyders Fawr, Fach, Y Garn & Tryfan. Stunning scenery and relatively compact area.
Skiddaw seems a simple up and down if you fancy the Lakes. There are some decent pubs there too you know.