Open your Key Commands Window (Option-K)
Logic Pro > Preferences > Key Commands...
Type Sample in the search field and you'll see the following options:
I've set my "Open Sample Editor" command to Ctrl-Option-Cmd-W. You can set it to whatever Key command is good for you.
By the way, "W" opens the sample editor at the bottom of the screen.
This command opens the sample editor in it's own standard window, not a floating window or a tab.
(It is NOT called a "Floating window". A floating window always stays on top of other window even when it is not selected. In Logic 8 only the Environment can be opened as a floating window...)
Hope that helps :-)