The Wizard's Vault, and whether it is worth your time
The most reliable income in the game for the least commitment — with one caveat about the weeklies that catches people out.
The Wizard's Vault replaced the old daily system and is, for most players, the single best return on a small amount of time in Guild Wars 2. It is also the one system where the game is unusually clear about what it wants from you.
How it works
You get a set of daily objectives and a set of weekly ones. Completing them pays Astral Acclaim, which buys things from a vendor that rotates by season. Finishing enough of the dailies pays a bonus on top; the same for the weeklies.
Each objective tells you exactly what it wants — complete three events, finish a jumping puzzle, deal damage with siege — and the API reports your progress against it precisely. There is no interpretation needed anywhere in this system, which is rare.
The part that catches people
The weeklies are worth far more than the dailies and reset far less often. A daily missed costs a day. A weekly missed on Sunday costs a week, and there is no way to catch up.
So the sensible pattern is to glance at the weeklies early in the week and let the dailies happen incidentally, rather than the other way round. Several weeklies complete themselves while you do the dailies anyway.
Claimed and completed are different states
An objective can be finished and unclaimed, and the reward sits there until you open the panel. This is the easiest free acclaim in the game and the easiest to forget, because nothing in the world tells you about it.
It also expires at the reset. A finished, unclaimed objective is simply gone when the period rolls over.
Whether to spend or save
We deliberately do not rank the vault rewards by value. Doing that properly needs a maintained valuation model — what a given item is worth changes with the trading post and with what you personally still need — and a ranking without one would be a confident-looking number with nothing behind it.
What is worth knowing: your already-purchased counts limit some rewards, so an item you have bought the maximum of is not an option however good it looks.