24" stands will be too short, I am using 28" stands from Sanus (available at Crutchfield) for my S36's (surround channels, also horizontally oriented)and thet puts the mid/tweets at about ear level. My S38's are on bookshelfs up front for now.
One caution, if you have small kids/large dogs that might bump in to the stand, you may want to go to a hollow metal stand with a wide base that you can fill with sand for extra weight (Parts Express has some of those) since the S38 is a lot heavier than the S36 (which uses a molded ABS enclosure).
Also, any stand of that height will have a relatively small top plate, usually 6 x 6, you may want to consider bolting on a larger plate ( made out of MDF and painted to match) so the S-38's wont be balanced on a small surface. Good Luck
I use pedestals from Hobby Lobby, similar to the post from Angelo.m... They were like some rosin, I was able to fill them some, they seem very solid now.