The research is going well
What's this what's this what's this??
But as for the rest of it, yeah, I think I'm familiar with what you're talking about... unfortunately, I don't know any simple solutions either, or I would have used them. :-/
It seems to me this malaise isn't dependent on how much fun you have the rest of the day, and there's no simple solution to it, but it will get better with time. And that could be completely wrong, but I have no answers either, so here's a quote from Doctor Who instead.
The way I see it, every life is a pile of good things and bad things. The good things don’t always soften the bad things, but vice versa the bad things don’t always spoil the good things and make them unimportant. And we definitely added to his pile of good things.
Now there's a good quote. Never thought of it that way before. Danke!
I've spent a lot of time in the last couple years thinking about (and personally dealing with) the difference between doing awesome things that usually require a pretty high energy state (one-on-one conversations falls in this category for me, although I also really love these) and satisfying a very different need for things that make me happy when I'm tired and need to rest and relax.
I'm not doing a great job with the latter. The former is, in my opinion, easier to control: plan a trip to CA, yosemite, Israel, teaching, game nights, math seminars, dinner with a friend. And MIT/ESP/MathCamp are great communities for active socialization. But the latter is, for me, a lot harder. I used to be able to manage a lot more of it solo - activities like hiking alone for a day or reading a novel series over a weekend or cooking for a night or making some kind of art used to pretty much cover it. But, I also have found that I'm now looking for... I don't know... a human connection in this more low-energy state, a small one that is simply happy that I'm there. It's hard to be unhappy when you're making other people happy in my opinion. Be it close friend(s), or someone you're dating. Are you dating anyone at present?
I don't know if this is close to what you're talking about. Personally, I relate a people pile of n very closely to a people pile of two - the pile of any number being special instead because there's so little pressure or necessary energy of almost any kind in the situation. Anyway, best I've got is to go back to really old friends and spend a day very casually hanging out - a picnic or something: hang out with a person who you know just likes to be around you and just be lazy with them for a bit. :) Best luck.
It's really interesting how many people have replied to me saying that they know the feeling well (I'm counting a couple who have poked me over IM). It's nice knowing that I'm not alone in this, though getting to know that through other people's sadness makes for an unfortunate victory.
I like how you've stated the problem, and I think it flows nicely with my complaints about not having a peer group (and to answer your question, I'm not dating anyone at the moment). That said, I don't follow your suggestion of "pile of two." Don't get me wrong -- I love spending a day hanging out with precisely one other person, and I've actually been doing a lot of that in the past few weeks. While it's a great experience, it's still "high energy" to some extent, even if it's not high energy while it's happening. The fact is, I can't spend a few hours lazily hanging out with friends when I feel like it because, well... they're not physically here (and I'm tired of giant AIM discussions for the time being). I have to plan to spend those hours a few days in advance, and this has the twin disadvantages of making things less casual and less prompt. I don't get to have my "hang out time" when I really need it.
But yeah. Low energy human connection is where it's at... I just need to find a place where it happens consistently.
A bit on a tangent: as a result of thinking about this for a while, I've also gotten a chance to observe that most of human population has these problems at some point. I think the pseudo solutions are bars and parties - drinking and hanging out when drunk seems to at least half-solve this problem for most people (Foo night football, crashing on the couch with the guys is a lot like a people pile...). And, the more successfully you've found a group of friends, the more your parties are geared to your interests and with people you know well and/or are more intimate with.
So, I'm not sure "find a place where it happens consistently" makes a lot of sense literally. You're right, people are happy in part when they slowly find/make a local group of friends who want to relax in similar ways and express that they make each other happy (expression is complicated, and takes a lot of forms including seemingly negative ones).
Anyway, I'm sure I'm oversimplifying... but, my guess is that, if you're going to be where you currently are for any amount of time, you should try to slowly build up or find a social circle and spend a couple years getting comfortable enough with them that you can almost completely relax. Note that you have to be able to take pride in making this social circle happy, or you won't find it fulfilling.
Um... I guess this is my summary of how I think people work. Good luck.