Bessenthwaite is a nice spot but a bit out of Keswick if you want to wander round of a evening for a drink go for something to eat.
Keswick is a smashing place, depends on your budget what accommodation your looking for but latterly missus & I have stayed at the inn on the square & really enjoyed it bit pricey but sod it, I’d also recommend Mary Mount Hotel great setting very chilled out, B&B wise Pitcairn is good as is the grassmoor but there’s ample choice of good B&B’s
Also just a short walk from Keswick is Portinscale, a small village with a few pubs & very good restaurant called the Chalet, café by day great for a good brew after a walk as you can end your walk & drop in, or a evening out as it serves great food.
Hope that helps.