Hiya, I'm from whitehaven on the west coast of cumbria, and from experience there's so much to do and see, your best way to go about planning is to think realistically about how far you want to travel to do sightseeing/walking/shopping, etc., then contact tourist info (kendal will have one) and ask for info. Also if you're staying in a B&B or hotel they'll know the surrounding areas. Remember that the main roads through the lakes aren't really 'main' roads and with tourist traffic a short journey can take a while! At least Kendal is on the M6!
Have a great time with the cumbrians, say hiya marra to them from me! (translation: hello mate)!
Oh and bowness, windermere, ambleside, grasmere, keswick are good to visit, but they are the main touristy areas, so look for somewhere off the beaten track for memorable scenery!
Lynn