On rainy days I would usually recommend staying inside and watching your favorite movie (Sleepless IN Seattle for). However at Canyon Ferry during our warm months, there are endless possibilities.
1. Many of the camp grounds have great little gazebos, pack a lunch and watch the weather move through the Canyon.
2. Don't like outside very much, well on the East Shore of Canyon Ferry you have O'Malleys Pub, one of my favorite places to go when I am out and about at the lake. Great food, fun atmosphere, outside dining and views of the lake. And yes, the owners are Irish!
3. West Shore of Canyon Ferry is more your cup of tea, you have the Yacht Basin, I have a family member who reports that their prime rib dinner is amazing, and with the best view of the lake, it is hard to beat!
4. A quick trip down to York, who is famous for the York Bar...great hamburgers.
Have questions on any of these places, call me I know them well.