Generally speaking my advice is to go with light but rigid stands if you have "springy" floors such as wood or heavy rigid stands if you have more secure floors such as cement of plaster. I would use spikes to couple to the floor in both cases. I also prefer one piece welded stands to the cheaper modular models. One exception to this may be Coincident speakers which are tuned to the speaker cabinet resonance as opposed to damping the crap out of the cabinet. I don't know if they are different, but it would seem that you would not want to over damp them because of their design. Using Pods (or cones) as Sam mentions can make a huge difference and it just depends on what type of sound you are looking for. I use tack right now, but have used both Pods and cones in the past as well as both types of speaker stands noted above. On the plaster based floor in the living room I am currently using Target HR70 (28") stands with sand (I tried lead and sand and did not care for the sound). Sand alone in my situation sounds smoother and more natural. I use a small accurate bubble level for the initial setup and then fine tune by extending a straight rod along the top of the speaker and then measuring the distance from it's tip to the floor. This seems to match the speakers quite well (especially when the listening position is out into the room) and it is simple to do. Others may disagree with part of what I have to say, but this is what has worked best for me in the past.
