I like puzzles where the answer is extremely simple, but hidden in a mess of unnecessary data. An example is the old one about the man going to St Ives, who meets a man with seven wives, and so on. One is tempted to multiply all the sevens to get the answer, but in fact only one person is going to St Ives, the others are going in the opposite direction. I'd suggest one if I could think of one.
Actually, it has a flaw because simply meeting the man doesn't necessarily mean they were going in opposite directions.
Here's a different one that doesn't fall into that category.
Johnny and Sue are brother and sister and go for a walk with their dog Spot. Johnny walks at 4mph and Sue, being younger, can only walk at 3mph. Johnny doesn't wait for Sue and they get further and further apart. Spot gets distressed and runs continuously back and forth between the two at 10mph. Two hours after they leave home, Sue arrives home again and Spot stops running. How far did Spot run?