I'd like to see a way for convenience spells - things like Teleport and DD, that dont give you an actual combat-related bonus, but just offer convenience and time-saving - avaiable (with sufficient effort) to any character.
I'm imagining something along the lines of the Phiarlan Pendant of Time, another convenience item, or the Eveningstar key, or the many Expeditious Retreat clickies. A Teleport clicky with 2 charges and recharges itself 1 charge/15 min - enough that if you use it reasonably, its always ready, unlike the Royal Guard Mask, which only recharges in-town if you sit in a tavern. A simple 1/rest DD clicky would work, too.
It could be a favor reward for a faction (Twelve?), so that it requires a significant investment in time/adventure packs to be obtainable, again like the Phiarlan Pendant and the Eveningstar key.
I dont think that casters would complain that this is stepping on their toes, either - new casters would still be able to slot these spells as soon as they were available, to immediately take advantage of the convenience if they wanted....but it would also let them free up that spell slot for something more practical during quests, if they went through the effort to obtain it. Teleport is, I think, the only spell that Arcanes can slot that has absolutely no purpose during a quest.