Guilds should have a central "bank" or "pool" of Crystal Energy.
I'd be very surprised if this hasn't been mentioned before, but I didn't find it on the search.
It has to be bought and provided by the players in the guild like normal, but is then traded or donated to the guild ("Guild Actions > Donate Energy"). Once there is energy in the pool an appropriately ranked guild member (officer or veteran maybe?) should be able to set a party option "Pay for Elevators from Guild Pool", so that all the guild members in a given party pay their costs from the guild bank. It probably shouldn't allow revives to be paid, as this allows a malicious or incompetent member to drain the pool stupidly quickly - pay for your own deaths, and learn to get better!
I know this is kinda achievable as it is, by trading CE around or by donating it to a single member who then clicks the "Pay for" option on all his guild mates in a party, but it's clunky and prone to mistakes / abuse.
Why do I want this? In my circle of friends / guild mates I have the most CE (still not drained the remains of that Starter Pack I bought, let alone stuff I've purchased from the energy market) but I either face the option of handing out chunks of it at random to people or have to actually BE in every party to pay for the others. I would very much like to be able to donate to a pool of energy that I know my guild mates can responsibly use to adventure while I'm not around, but not to use for crafting (being given a free ride in crafting costs removes a large portion of the progression in the game). I'd like to hope that as guild members improve they will start to donate CE back into the pool (if they don't, we can always find new members who share our ideals!), and thus pay for other members to adventure and reach a similar position. I think this would help to create a steady demand for CE (from both the energy market and from Three Rings themselves), but also helping to perpetuate the guild as a whole.
Maybe I've missed something here, but this strikes me as a win for all involved. Poorer or newer guild members get to adventure more often with their guild mates, while also stimulating demand for CE from the guild as a whole (maybe more than the individual members themselves would generate, but this is speculation based on the idea that they will adventure more and therefore burn "excess" CE being stored up elsewhere in the guild).
With good permissions, this would be awesome.