> - System design at ~whiteboard still feels reasonable / CS basics.

Bingo. Timeless classic for good reason.

Code review also can be good, not in a "can you spot the 17 bugs" way, but rather as a tool for discussing what makes code good, what make a code-review good, what are the tradeoffs in this particular section of code, what tests or other safety checks might you want to add to this particular code, etc.

I prefer to talk through a code review with the candidate. I like to get a feel for how they approach another developer's code, the type of questions they ask, and whether or not they have a sense of situational needs.

It's worked well for me so far.

I'm not a fan of whiteboarding or on-the-spot code examinations. I feel the ability to communicate effectively about code and algorithms, critique in an empathic fashion is far more important.

Similarly, I feel that curiosity is one of the strongest skills a developer can have, and this is not something that can be demonstrated through coding exercises.