If you browse the search engine for what to fill speaker stands with, you'll find a lot of varying opinions. Some prefer kitty litter, some all sand, some shotgun pellets, and some a mixture of all of the above. There seems to be a repetition in some posts that filling only to the 2/3 level gives best results. I guess some people feel that you can over-damp the stands, resulting in a duller sound. I'm not so sure. I currently have Skylans in my main system and Lovans in my bedroom system. Both are filled to the brim with playground sand. Maybe I'll try the 2/3 full method. Speaking of Lovan, these new Jazz series look interesting:
http://www.lovanusa.com/index.php?cPath=1_9&osCsid=8429fda884027e95d3266782b84cce31