I like the last shot the most. I've found that even 300mm isn't enough for shooting from the beach. Recently got the Sigma 150-500 and I'm very pleased. If I could afford a 600mm f/4 I'd get one, but the children wouldn't get fed.
There's the other approach - get in the water. However, this is also not cheap if you want to use decent equipment. A good surf housing - no underwater housings don't take the pounding that surf camera housings do - ain't cheap. It seems that most 'in-the-water' photogs use wide and fast lenses to shoot surfers, again not cheap. Then there's the flippers, wetsuit etc as well.
So far, I like the idea of keeping me and my stuff relatively safe on the beach and snapping away. Plus, every now and again I can 'test' the zoom's colours on some bikini clad sunbather