I would like to be able to sort my items by sets. Mostly so it's easy to return to a lower level dungeon.
What do you mean by "sort my items by sets"? Anyway, the UI offers plenty of functionality to sift through your collection. You can filter items by slot (click on any of the slots of your characters or pick a slot from the dropdown menu) You can filter by typing card/item names, card type, and much more by typing into the text-box (special keywords are available too!) You can sort items by level/rarity/tokens cost Also, you can store/load whole party setups by clicking on the store/load button on the bottom-right corner in the keep and the pre-battle screens.
The first three bullet points still require me to sift through items looking for the right ones. PitA. The last one is something I had forgotten about, having only gone there once however having 'bags' I can specif specific it sets to would still be nice. So when I click on a dungeon and it tells me I am the wrong level and have to have some of my items replaced, I can just grab something out of the appropriate bag. I can't believe I forgot about the keep, that's hilarious.