Personally, I have no intention of ever utilizing the following rules, but it goes into the Game Design theory I was talking about earlier:
Daily powers, and encounter powers, are used partially on a Use Them Or Lose Them basis. This can be contrasted to consumable items and powers, which are not Use Them Or Lose Them. My own (FULLY ANECDOTAL) experience has been that players tend to be a lot more willing to use the former than they are the latter-though, in a total pinch, because they have to use consumable items to win, they will, as no one wants a TPK. The exception to this is when consumable items are so cheap-as is the case with low level reagents at mid to high paragon and beyond (prior to the rarity rules)-that the real expected cost of the consumable is so low that it might as well be something akin to an At-Will.
As I said, I don't have a problem with this mechanic-it encourages players to use every part of the character build, so to speak, but if you happen to like the idea of there always been a trade-off between using a power or not, at the end of an Extended Rest, consider rewarding characters who have unspent daily resources. The reward should be proportional to the number of encounters faced over the course of the day, the power (probably simply related to level) of the power, and any other factors concerned. This has the result of making burning off daily powers a little less desirable because of the associated opportunity cost. It does, however, put martial Essentials classes (barring the Assassin) in a bit of a pickle, especially considering how controversial they are to begin with.
That being said, it's not that it's complicated-a daily power that goes unspent is a one-time resource that wasn't used and as thus is wasted. Consider giving a "bonus" consumable power of comparable level, with a rarity based on the difficulty of that adventuring day. Obviously, common consumables are little more than worth 1/5th their level as bonus treasure, but uncommon and rare consumables are a major benefit.
But be prepared for the last fight of any given adventure to be a lot more difficult-your characters may start hoarding consumables, but whether or not they actually use them depends on their response to Use It Or Lose It free resources.