I have a max 1366x768 screen resolution.
My WinXP laptop is 1280x800 and Spark fits perfectly on that one, but my Win7 laptop's screen size is like yours, so I've noticed that too.
But, usually I use that one with an external screen above it, so it turned out a cool configuration to test Spark full open Top, Center and Bottom all at once. ...which, btw, has some GUI issues that I already reported.
When/If I have to use only the 1366/768 screen, I'm usually happy with moving Spark's window as up as possible cutting out the title bar as much as possible, giving me access to all the usable area of it. Not a perfect solution, but usable, nonetheless.
Also... it's possible to resize its window and scroll to get the usable area within visible range, which is also nice (uh... at least as standalone. I'm going to leave standalone testing and start Live 8 VST tests today, so... I'm not sure if what I just said holds true as a VST
EDIT: Window resize also works when as a VST (as expected, but I had to check).