There are plenty of places to visit around Windermere especially west/north of Ambleside. Rydal Water,Grasmere (try white moss for views above), loughrigg tarn (great views from loughrigg fell), blea tarn (side pike has great views but it depends if you are happy with a little climbing/scrambling). Tarn Hows is nice for a walk around.
Derwent Water is ok but Ashness Bridge and Derwent Water Jetty have been done to death, and there are usually a huge number of people on ashness bridge. Thirlmere looks very good especially for reflections.
Bing maps have an OS maps layer so you don't need to buy maps just to have look what's about.