Interpretation of the adjective "outstanding"

Solution 1:

If you think about the word outstanding itself, you'd notice how it generally means "unique in a group of similar objects or people (stands out, get it?).

It thus can both refer to something that is not-yet-done (while it's supposed to be, because the group that it belongs to has mostly done stuff), but it can also refer to a certain positive quality of uniqueness.

For me, however, the common idiom seems to be to usually use outstanding to mean astonishing, great, impressive, unique, unless followed by something that explicitly implies a task-based logic:

This is outstanding work, Harry Potter! (surely means 'great work', not 'work to be done').

I'll make a list of some outstanding tasks. (one can argue that the speaker has great tasks to do, but he/she probably meant not-yet-done).

In the end, it's all about context. In your question:

What are some outstanding places?

it seems a bit awkward to assume either interpretation. I would've said:

What are some places you're planning to visit?

Or:

What are some places you haven't yet been to?

Or even:

What places are on top of your list?

But this is going outside the scope of your question.