I recently placed my Maggies on a slab of 2" solid maple (from Mapleshade Records), and was very pleased with the changes. I had tried other sizes/types of wood previously that did not really do much. I believe there are also benefits from elevating the speakers a few inches.
Also being concerned about the stock stands that made the Maggies wobble when pushed at the top, I had custom stands made. The combination of the maple slabs and custom stands has really brought things together for my system. I also took my Maggies apart, and built an external xo prior to adding the custom stands. I was really amazed at how much detail was being lost by the stock stands. Bass was improved after adding the stands which I was anticipating, but I was surprised how everything else was improved throughout the range. Grant's stands come with 4 threaded brass cones per speaker stand, and the rear struts are hollow to place sand or whatever material you may want to use.
Here is the website for the Maggie owner (Grant VanderMye) that custom makes stands for the 1.6 & 3 series Magneplanars. These stands came recommended by individuals over at the Planar aslyum at AA, so you can do a search and get additional input.