A day fishing with Dad is priceless and that sorta goes without saying... . weird how I neglected to mention that.
Take a kid fishing, even if they don't like it and the weather is horrible and you catch nothing but the biggest thing in the lake (the bottom)... . they'll remember the time spent with you. I've spent many hours trolling for all kinds of fish, and I'm not the fisherman my Dad is... . but I'll always hold those memories dear, for one day I may be faced with the reality of not having him around at all.
Matt