The phrase "peaks and valleys" refers to the highs and lows of a situation or experience. There are plenty of synonyms that convey a similar meaning. For example, "ups and downs," "highs and lows," "ebbs and flows," "rollercoaster ride," and "mountains and troughs." Each phrase brings its own connotations and context to the table to paint a fuller picture of the range of emotions and experiences within the phrase. Whether it's the excitement and nerves that come with a rollercoaster or the steady yet unpredictable flow of the ocean's tide, these synonyms allow us to express the ever-changing nature of life's journey.