The listening areas in all my houses have had oak floor over subfloor over wood joists. I have found cones to perform fine with my larger sized speakers. I also have used Sound Anchor stands with all of my speakers for added weight, stability and protection of the speaker base. I like cones better than skinny spikes or rubber type footers. Wellfed, I find it interesting you like the Fat Black Dots better than Audio Points, and would be curious to hear what improvements you noticed. BTW, are the Black Dots similar in substance to a hockey puck, harder, or softer?
To protect the floor, I have used Sound Anchor Cone Coasters [http://www.soundanchors.com/page20.html], a stainless steel disk with a small point for the cone tip and a special teflon type pad on the bottom. These also allow you to slide the speaker around to position it without damaging the floor.
I wouldn't worry too much about positioning over the joists. You have large heavy speakers with an 11 by 24 inch footprint, so your floor/subfloor combination should distribute the load over at least two to three of the floor joists regardless of your specific positioning. If the house is old, so that the subfloor was not originally glued down, you may want to use some fasteners from underneath to anchor the subfloor to the tops of the joists in the area of the speakers (this is commonly done to eliminate floor creaking in older houses). Another thing you can do if you can get to the underside of the floor, is to add perpindicular bracing between joists in the area of the speakers.
A last consideration nobody has yet mentioned on this thread is that some have reported good results using Symposium Svelte Shelf platforms under speakers. They can also be used between speakers and stands, which I have been curious about trying. Let us know what works for you.
To protect the floor, I have used Sound Anchor Cone Coasters [http://www.soundanchors.com/page20.html], a stainless steel disk with a small point for the cone tip and a special teflon type pad on the bottom. These also allow you to slide the speaker around to position it without damaging the floor.
I wouldn't worry too much about positioning over the joists. You have large heavy speakers with an 11 by 24 inch footprint, so your floor/subfloor combination should distribute the load over at least two to three of the floor joists regardless of your specific positioning. If the house is old, so that the subfloor was not originally glued down, you may want to use some fasteners from underneath to anchor the subfloor to the tops of the joists in the area of the speakers (this is commonly done to eliminate floor creaking in older houses). Another thing you can do if you can get to the underside of the floor, is to add perpindicular bracing between joists in the area of the speakers.
A last consideration nobody has yet mentioned on this thread is that some have reported good results using Symposium Svelte Shelf platforms under speakers. They can also be used between speakers and stands, which I have been curious about trying. Let us know what works for you.