I'm working on a board, and will be using an LT3451 DC/DC converter to convert from +5V to +30V, and I'm trying to figure out how to interpret the "Layout Hints".
Is the attached diagram just for the actual component layout, or should there be large copper planes in the sameish design as in the figure (ie: should it have large blocks of copper instead of normal traces)
Yes, they provide the gray areas for a reason.
More particularly, low current traces (SHUTDOWN, and the feedback node on R1 and R2) don't need to be any shape, and can be thin. The rest should be thick traces approximately as shown, or pours. The L1 pad will be mostly for thermal reasons; it doesn't need to be a thick trace for electrical reasons (because L1 is effectively a thin, very long trace, wrapped up, after all).
Tim