Why not change the background colour of the speed tape and altitude tapes when the autothrottle /autopilot is on/off.
Crazy concept: the altitude tape runs down the screen as altitude increases, which is logical. It means that bugged altitudes are higher than the pitch line on the horizon display, so pitching up to meet an altitude bug is intuitive. The speed tape runs in the same sense as the altitude tape, running down the screen with higher speeds at the top - but this results in the bugged speed in the incorrect sense in relation to the pitch line on the horizon display - that is, if you bug a higher speed then the bug is higher on the screen than the pitch line, but if you pitch up to meet the bug (as you do in the altitude case) then you reduce speed - in this way it operates in the incorrect sense. If you reverse the direction of the speed tape, so that it runs up the screen instead of down, then you can "pitch to meet the bug" in both cases.