I've used SVG for illustrations and photographs which I wanted to reproduce in the original landscape mode, so I could rotate the caption 90 degrees. I've done it in e.g.
Eivind Astrup: Blandt Nordpolens Naboer
I'm not sure it's worth it though; SVG support can be patchy and unpredictable, and more readers have support for flipping between portrait and landscape mode than have reliable SVG support.
My favourite use of SVG is to achieve flow around ragged images as described in this
post by Jellby. This paticular solution has the advantage that the images can be scaled. See e.g.
Fridtjof Nansen: Eskimoliv, chapter 4.
For scaling of other images I just set the width attribute to a percentage value, that seems to handle scaling in all the readers I've tried.