Greetings and salutations!
Today, I found myself thinking about line length. There are so many different ways of using the line to enhance your poem: you can decide to use short or long lines or a combination of both to control the pacing, you can focus on which words you'd prefer to end a line to put particular emphasis on the most important, you can consider whether or not to enjamb which also can determine the rhythm of the poem, and/or you can rhyme the end words to give the poem interesting sonics. There are many other considerations I've neglected to list.
I believe that focusing on the number of syllables in each line can open up the way you think about your poems: using a set number of syllables can make all your lines long or short, can force you to be creative with end-words, can make you consider enjambment in a new light. Because you are placing a mechanical framework upon your words, you find that you sometimes pay a lot more attention to the words you choose to form an idea than you might if you were writing freely.
Some of the most famous examples of syllabic verse are the Japanese forms of haiku, and tanka. Additionally, there is the Alexandrine, a French syllabic form where each line has twelve syllables and generally one caesura.
Because English does not traditionally have many forms that use syllabics (mostly because English is accentually, rather than syllabically, rhythmic) does not mean that there aren't great poems written where the poet counted his/her syllables. Here are a few:
Philip Levine What Work Is (averages 9 syllables per line)
Marianne Moore To a Steam Roller (each stanza follows a syllabic form: 5-12-12-15)
Dylan Thomas Fern Hill (you tell me what the syllabics in this poem are!)
This week's spark: write a syllabic poem. Have fun!