Thumbs, whether the image be cropped or scaled (a different issue):

The two different sizes, portrait & landscape, are not aligned at the baseline so the rows aren't "even", every row contains a different number of images and your eye cannot follow across. Is there a way of aligning them up? Using Default theme.

You can set up the css to provide equal space for all images. This has been done in the stopdesign theme for the "slides" it uses as thumbnails.

Thanks, will poke through stopdesign CSS and find the code to add to my CSS. Do you know offhand what portion I should look for?

Look for things taged 'thumb'