Using the Hide command you can hide the data and formulas from "inquisitive minds". But some of them still can use Unhide command. Nevertheless you can completely hide Excel spreadsheet so that it will be needed some VBA programming to unhide it.
You can make a worksheet more visually appealing and easier to read by centering text across multiple columns. Often you do this by merging and centering the merged cells, but it is not the only option.