Microsoft Excel has hundreds of functions and commands, but even so there are some things the Microsoft engineers failed to include. One of my recurrent annoyances is the lack of a command to unhide more than one sheet at a time. Hiding several sheets at once is very easy: you just select them by holding down the Ctrl key and then hide the group from the Format menu. The unhide option on the other hand presents you with a list of hidden sheets where you can only select one item to display it again.
When working with large files and lots of sheets, I prefer to hide the sheets where data is stored or where intermediary calculations are performed, and leave only the final results and charts visible to improve the readability of the file. But Excel makes it hard to bring back these sheets if you want to edit them again.