IMO. The things I'd like would be.

1. All characters on the same world sharing a private home if purchased by the player.
2. The minion/mount/triple triad card/orchestrion/emote lists being shared account wide. Just drop some allegan coins or something small for repeat quest rewards.
3. Friendlist/blacklist account wide
4. A small shared storage safe accessible from Inn rooms or a furnishing that can be placed in a house/apartment that all characters on the same world share.