I filmed a video for a photographer last week and I am currently editing it. I basically just followed her on one of her shoots and got footage. She sent me her finished pictures and wants them incorporated into the video, which is great.

The only problem I am having is with her "vertical" photos. All the photos are fantastic, but the ones that are horizontal obviously fit into video much better. She has some fantastic photos that are vertical but I'm struggling to get them into the video without looking out of place. If I leave them as is, the black bars on the side look too different. I tried using ken burns but the photo would be so zoomed in, it wouldn't look right (if that makes sense.

I'm struggling to come up with a solution. Any ideas?

Most common I see is the photo, zoomed to fit, in the background, often blurred or at 50% opacity or so. Gets rid of the black with color, but nothing to draw the eye away.

You might try and put a solid color slide in the background, with a color, that suits the photo.
Or else use a still from your own footage in the background.

+1 to the tips offered above. Also wanted to add that sometimes we are our own worst critics.
We obsess over every last detail (which is good in a professional sense).
But sometimes our customers are unaware of what we were even obsessing over.

That's a good point Vince. I ended up using a blurred/zoomed in version of the photo and it looks fine. Thanks guys!

One other possibility would be to use multiple photos tiled across the screen?