Improved Tab Navigation
Provide a better tab list for navigation than the one supplied by SSMS when there are many tabs open, for instance a resizable "navigation" window (or even a navigation tab) that easily allows filtering/grouping by server instance, database, user defined, etc.
As a complement to grouping tabs would be to allow naming, saving, closing, and opening of a "tab group" - related queries/script files that do not make up an SSMS "project" but are used for a particular purpose or go against a particular database, etc (user determines grouping criteria, see above). Furthermore, activating a tab group would bring its members to the forefront (left), hiding a group would de-clutter the tab layouts when work is not complete but temporarily working on another issue (another tab or tab group), etc. Tab group color coding could be an alternative option for tab coloring, etc.
Charles Barest commented
I like the idea of multi-selecting multiple tabs for close or deletion. Also if the Tab Names could be displayed, this would be a big help. Often I do a Rename Tab (on open tabs) for temporary scripts I use while working on particular projects. I would LOVE to see those names displayed in the Open Tab History to make it easier to identify than having to remember that 'SQLQuery38.sql' is actually my temporarily named tab: 'GetEmailTemplate Worksheet'. Thanks