How do I shrink all files quickly for all databases?
When you do "Tasks -> Shrink" from the GUI it actually issues a DBCC SHRINKDATABASE command behind the scenes. Try it. When the dialog box comes up, don't click the "OK" button. Instead, click the "Script" button. You'll see the command in a query window. Combine that with a query on sys.databases (leave out master and msdb), and you can make a script to shrink all of the databases.

For example (taken from jcolebrand's comment):

SELECT 
      'USE [' + d.name + N']' + CHAR(13) + CHAR(10) 
    + 'DBCC SHRINKFILE (N''' + mf.name + N''' , 0, TRUNCATEONLY)' 
    + CHAR(13) + CHAR(10) + CHAR(13) + CHAR(10) 
FROM 
         sys.master_files mf 
    JOIN sys.databases d 
        ON mf.database_id = d.database_id 
WHERE d.database_id &gt; 4;


Copy the output of that query and run it to shrink all your files.