Page up/down without changing position on page
It would be great to have the ability to move forward or backward by one page without altering the zoomed position on the page. If this feature already exists in Acrobat, I haven't found it yet. The keyboard page up/page down buttons only advance one page when a full page is displayed on the screen. Once you zoom in, the keyboard page up/page down buttons simply cause the display to scroll vertically in "chunks" until it reaches a page break and then it jumps to the next (or previous) page. Acrobat's "Show next page" buttons are also deficient: they advance to the next (or previous) page, but they also reset the vertical position to the top of the page.
In the building design/construction industry, it is very common to have several pages of floor plans for the various storeys that are horizontally aligned from one page to the next. When reviewing floor plans, it would be nice to be able to zoom and pan to a particular area of the floor plan and then quickly compare to the storey above or below by moving one page forward or backward while maintaining a constant "camera" position on the page. I doubt this feature would be difficult to add and maybe assign a keyboard shortcut to (say alt-page up/alt-page down).