The conventional wisdom is that 'said' is considered to be the best word to use in a dialogue tag, mainly because synonyms tend to be distracting and noticeable and take away from the dialogue itself. The way someone says something should be self-evident (screenplays are a good source for seeing how effective this can be).

The brain is astute enough to be able to tell the differnece between real variety and half-hearted attempts. So:

Peter ran up the stairs, sprinted along the hall, and hurried into the room.

even though I'm using different words for 'run' it just feels like I went thesaurus-crazy, and that's how it often feels with 'creative' dialogue tags. This is exaggerated by the fact that dialogue tags appear in large chunks of writing at the end of each line, forming an eye-catching pattern.

However, you can still throw in 'he whispered' or 'she shouted' where you feel it's imprtant to specify how someone speaks. Just don't overdo it.