I think it depends on what types of activities you think your kids would truly enjoy.
Kids Clubs seem to have lots of activities for kids, but they are not things that my kids would enjoy. For instance -- video games. My kids don't play those at all. They watch TV, yes, but not tons and not that many movies at all.
However, they do like to read and play games and draw, and that was what they did with their Fairy Godmother babysitter. She arrived about five minutes early and brought a gigantic bag filled with age-appropriate toys. When we left, they were setting out a board game. I later found out that they also worked on crossword puzzles, played more games, drew pictures/colored, and worked with Playdough. She also read them stories before they fell asleep. It was perfect, and the kids were rested enough to still hit the parks in full gear the next day.
This was our experience in May, and I would not hesitate to recommend Fairy Godmothers to anyone. They were much more than we expected.
Linda