I liked the ability to save multiple tabs as bookmarks however this would be a lot more useful if the user could define a root folder under which these were saved and maybe also be able to enter a name for the sub-folder those tabs are saved to.

Currently sets of saved tabs are saved under "Other Bookmarks". A user defined location would all for the possibility of placing that within the Bookmarks Toolbar (or where ever else the user wants) which would be easier to select if you have the toolbar showing. Or, even if you don't want it in the toolbar, being able to set the location and name of the root folder would make it clearer what's in it, like changing it to "Saved Tab Sets", or whatever.

And a user defined name is just an extra convenience, especially if all the the tabs saved have names that aren't helpful or don't indicate their content. These can be renamed later by editing bookmarks, yes, but being able to name them meaningfully when saved removes the need later.