I remember reading an article in 'Flying' magazine, written by 757/767 Captain Thomas Block. He wrote about one time when he was using spoilers in the descent and when it came to level off he had forgotten the speedbrakes. A gentle reminder from the right seat put things right.
He then went on to write about (I think) an American Airlines 757 that due to a navigational issue, crashed in mountainous terrain. I believe it was the subject of one of those Air Crash Investigation programmes at one time.
It was subsequently found that it had crashed during the descent phase, and recovery showed the speedbrakes were deployed at impact, although I think the CVR/FDR showed the aircraft crashed while attempting to climb. The crew had used the speedbrakes for the descent and at the time of trying to climb, did not retract the speedbrakes. I do not know whether the application of speedbrakes was fundamental to the crash or not. I guess it certainly didn't help.
His article was based upon not being able to think of a scenario when thrust and speedbrakes in combination would be desirable? And why the spoilers did not auto-retract in the air with power application like they do on the ground. Is this still the case or have systems changed since then?
EDIT: Just read Saskatoons post... he knows what I'm talking about!