Well, it's more like:
- I want the option to introduce a single encounter that sucks up ALL the party's resources in about an hour of table-time (about 5-7 rounds, I guess)
- I want the option to NOT do that, too. In the same campaign. Without making the characters re-write their sheets.
That doesn't seem like it should be impossible.
Then I think you need some new monster classification that is rather orthogonal to the minion, standard, elite, solo dimension. You need monsters that can take hits like a solo, dish it out like mulltiple standards--yet have a plausible reason why they can't focus fire (whether mechanical or story).
Crude version for illustration -- The Single Encounter Enhancer Template: When applied, a monster can make up to five attack per round, but never more than one attack on the same target. However, it emits an aura that allows the effects of short rests to occur after every third action.
Less crudely, a template that had a twisted form of ranged vampirism, where the creature drains hits points steadily, but at certain points it triggers the ability use surges on those drained. This is similar to the zone ideas that were suggested by someone earlier, simply attached to the monsters instead. I suppose you could also do this with some form of twisted magic. (Sufficiently twisted that the players wouldn't want to use it. Perhaps using it causes all kinds of slow side effects, like the 1E ghost aging on steroids. Or you get a Dark Crystal vibe going.)
Edit again: Girl Genius type idea--so wacky, it just ... might ... work!

You change absolutely nothing about the encounter itself, whatsoever. But in the location, carried by the creatures, activated by a curse, whatever--a "resource bomb" goes off as the encounter starts. Boom, everyone loses down to only having a few surges left. There is a small chance that some modest hit point damage is done, a daily gets drained, magic item uses are stunted, and so on. In effect, this bomb acts as if you just played out 3 earlier standard encounters, with more or less average results. (I went easy on the dailys, since you said you wanted to keep those largely intact.) The single encounter of the day is really the last encounter of the day--the most interesting one.
To be nicer/meaner (depending on you and the players exactly which this is), you might tie avoiding the effects of the bomb to a skill challenge. It isn't something that you can totally avoid, but complete success with a skill challenge limits it to only losing the surges, while failure progressively takes away the other stuff.