looking for a theme where a nice large graphic can go at top

How large? The default theme has a “large” header space…

My site uses the Relaxation 3 Column theme by Clemens Orth… https://clemens.orth.me.uk/2005/05/15/wordpress-theme-3-column-relaxation/

I change my header graphic every other week or so.

This one ?
https://www.thekatswhiskers.com/

Sorry to point out the obvious but what’s wrong with Kubrick?

You can change the header space in the CSS.