I'm a bit late to this thread and didn't read the ENTIRE thing, but I'll throw in my .2 cents anyway ;-)
I've had several situations that seemed to be an engine problem (I'm ASEL only), enough to raise the old pucker factor. Within 30 seconds or so, I was able to determine it wasn't a problem, but really starts to make one think. Following are some of those thoughts.
* Where is the nearest landing site, on or off field
* Start diagnosis of the potential problem. If it's a real problem, this step is skipped and start into best glide and other more critical things, but we're talking a possible problem in this scenario
* Where is the nearest (by time) field. Keeping in mind a field 90 degrees to the left might be closer than the field 90 degrees to the right at the same distance, but the winds will cause you to get to the other quicker
* What's the terrain to that field? I might rather go to the further airport if there are farm fields along it's route.
* Is there a different route I can/should take to the airport that provides better off-field options?
* Should I continue on my current heading or turn to that alternate airport? Depends on the situation. If I still haven't determined what the problem is, I might turn at this point.
* Where am I heading? What's the terrain like in that direction? Am I bucking a headwind? What's the weather going to be? Has the problem cleared up? If I don't like the answers to any of those questions, I turn to the alternate field.
* Lastly, do I need to (or should I) reduce power to continue my flight? If so, this would most likely precipitate a turn to the alternate airport, then reduce power to just enough power to maintain altitude.
Also keep in mind that my personal priorities to minimal effects on society are as follows:
* First priority is to do what I can to prevent injury to anyone on the ground
* Then do what I can to prevent property damage to structures on the ground
* Then do what I can to prevent injury to passengers
* Then do what I can to prevent injury to myself
* Do what I can to keep the aircraft flyable after the "landing"
As far as the multi-engine debate: My personal feelings (remember I really don't have any practical experience in AMEL), like everything else, it depends. I'd say it first depends mostly on proficiency. Secondly it depends on conditions. They both have advantages. I was once told in a single engine, you have less decisions to make in a single engine, where with a multi-engine, you've got a lot more options and maybe not enough time to make the right decision. Of course, there's a big difference between cruise and other phases of flight. I'd also keep in mind that since most single engine are not FIKI and many twins are, there's a chance the twin might be in known icing conditions.
But personally, would I like a second engine as a backup? You bet. If an inline twin aircraft were more practical, that, I think, would be the best of both worlds. It would be really nice to have an inline with the option to shutdown the second engine during cruise to save on fuel, but have it for all other phases of flight. Maybe a gas powered primary with an electric second pusher as backup. Hmmmm
And don't get me started on AS/MES, I'd love to have an amphib and open up all those water landing options in case of engine out.