I just submitted two FRs. Since Reaper's MIDI workflow is very clip-centric, and makes it much more difficult to manipulate entire instrumental parts compared to other DAWs (such as Sonar), I submitted FRs for two track actions:
http://forum.cockos.com/project.php?issueid=3471 - Open selected track(s) in MIDI editor and
http://forum.cockos.com/project.php?issueid=3472 - Glue all items in selected track(s) in MIDI editor.
By using these actions, a user can combine and manipulate whole tracks full of MIDI events without having to find and select every single MIDI clip.