More info about what your speakers are, how you're using them and what your setup is like would help.
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I have 24" tall speaker stands right now and they're about right. I like my speakers close to about ear level (i usually shoot to line up with the tweeter, more or less), or a little lower since I lean back when I'm listening most times to my stereo.
For surrounds, like yours, I worry less about height. In my home theater I have my surrounds on 30" stands so they are above ear level but by not by a whole lot. I preferred that to having them hidden behind the top of my couch.