Here is a design that I will be making when I have my new listening chair. Your design philosophy is spot on, thicker wood and more weight = less vibration. Herbies Fat Dots under your monitors would also be a good idea.
Do a "DIY Speaker Stand" search and check out more designs.
Good-Luck
http://www.tnt-audio.com/clinica/stubby_e.html
Do a "DIY Speaker Stand" search and check out more designs.
Good-Luck
http://www.tnt-audio.com/clinica/stubby_e.html