Seeing how everyone makes suggestions for old sets being reissued, lets make some suggestions for specific parts/combinations too since that makes up most of the DS catalogue.
Here's a few.
-Storage items.
A small set consisting out of various chests and barrels, all empty.
-Treasure.
There is a set like that yes, but it does not contain gold pieces oddly enough.
For this one I'd suggest two sets of gold and two sets of silver pieces being included, enough to fill a large treasure chest.
Aside from that also some cups, a crown, a vase, lamp, etc.
-Castle servants.
Set of three clickies which are generic castle servants with neutral colors.
Includes a maid, a stable boy and a herald. Accesoires can be a broom, a bucket and a scroll.
-neutral horses.
Right now there are only show horses and such in DS I believe, not horses that are suitable for historic themes.
Just a nice little batch of about five horses in different colors with neutral saddles would be good.
-Medieval armory.
Set containing about eight soldier helmets and breastplates, six neutral shields, four spears, four swords, two crossbows, two bows, four quivers with arrows, two flails, two axes and two different full sets of knight armor. (neither being the overused fat armor)