Not sure what you mean by my “conclusions”
One thing I’d like to clarify is that, in the second case, there was really no big secret that my friend and I were trying to bring off. Yes, it would have been a surprise but I wasn’t really doing a bad thing by “blowing” it as I may have made it sound.
Your conclusion in the first case was the action of leaving the light on. In the second case it was the action of telling your friends about the possible arrival.
-Kris
Tell me what’s confusing you and I’ll try to unconfuse you. 
-FrL-
The key point that will allow us to determine whose characterisations of your reasoning is correct is why did you do what you did? Is it just because one gain will “make up for” one loss? Or is it reasoning revolving around the feeling that if you spoil the surprise, or leave the lights on, that somehow feels like it will make something happen?
Why I did what I did? Again, I realize that there is now cause/effect between what I did and whether my friend or the maid came.
In the first case, it started out as a cost/benefit decision… take my shoes off and walk thru the whole house again to save a few pennies. I think I decided to screw it… and then the thought of the possibility of it costing me more if the maid didn’t come popped into my mind but was immediately offset by the much greater savings that would result if I didn’t have to pay her…
Not sure how to better explain the second case. I’m curious whether there is anything common to that thought process and that of the first. As I said in the OP, this kind of “reasoning” often pops into my mind and these were just two recent incidents that arose after I decided to post this question when I could come up with some examples.
In that second case, I didn’t gain much by telling my two friends that the third might show up. It did allow me to contribute to the conversation which I rarely do (I’m more of a listener than talker unless I really have something worthwhile to convey). You could also say that it benefited everyone for my two friends to know that the third was in town in case they definately wanted to go out of their way to get hold of him.
Again it was almost after the fact that I rationalized that blowing the “surprise” would be more than offset if he actually did show up.
Thanks for the clarification. I think I understand Frylock’s confusion over my position now. I’m not sure whether there is a name for this, but it’s got something to do with framing and bundles of choices. It’s related to the prospect theory mentioned by kalmia latifolia and to mental accounting.
The more I think about it the more it seems like it’s really cost/benefit.
In each case, the cost/benefit at the outset is really insignificant.
However, step two is planning for contingencies…whether the maid or my friend will show up. At that point I determine that the cost is less than the benefit even after including the fact that I could lessen the cost by acting differently at the outset.
Make sense?
As my post number three above shows, though, when you add up the costs and benefits you describe in the OP, it turns out that leaving the lights on/telling the secret is the costliest choice, not the most beneficial one.
-FrL-