How I award XP in my OSR games has been a changing process over the existence of the campaign. I'll explain when appropriate why I think each thing has a balance to it (or not) as a reward and add some of my reasoning.
To simplify this post, I will assume we're rewarding the XP in a dungeon, but it could be another type of adventure.
Monsters: Assume that when I refer to 'monsters' I also include other forms of enemies. I award XP for monsters as in the default manner of 'Crypts & Things'. I like that it has a handy chart for how a monster's special abilities would specifically increase its worth. 'Castles & Crusades', the system I use (although house-ruled) has something similar but it also requires me to keep track of the HP of a monster to calculate its XP worth. While I initially appreciated that, it ends up giving me more book-keeping to do and an average XP evens out over the course of a campaign, since sometimes the monsters will get less than average and sometimes they'll get more. (Plus I often roll a monster's HP during the game on the spot.) I don't award XP for avoiding conflict with a monster, when doing so the players are already rewarded by avoiding the risk of death. (Even lesser monsters can weaken you by a few HP, which might make all the difference later on against a more powerful creature or trap.) Monsters don't give that much XP and they are dangerous, but once they are killed their XP worth is ensured to you if you survive the dungeon.
Traps: They are a challenge and they can hurt or even kill you, so yes I think they should give XP when disarmed or survived. I use the rules given in 'Machinations of the Space Princess' for those. The philosophy behind their XP worth is basically the same as with monsters. Unlike with the monsters though, if you knowingly avoid a trap (and don't just avoid it by accident without even knowing it's there.) then you DO get its XP worth.
Treasure: 1 xp per 1 gp. Back to being the main source of XP in my campaign, it's not dangerous in itself as a way to win XP but you need to prepare accordingly and you have to bring it back to civilization, so in many ways it's the easiest XP to lose on the way, therefore I think it balances out.
Magic Items: When I include them, I do award XP for them. A lot of people argue that they are a reward already, but oddly enough many of those who say it still give XP for gold pieces, which are also a reward in itself. Anyway, I use the XP worth from 'Castles & Crusades' but do it a bit differently when it's time to award said XP; I actually split it among the party, I don't give it all to the person keeping the magic object. The magic item needs to be Identified (or otherwise somehow triggered, or even drank in the case of potions) to receive its XP worth. If the characters don't realize what it is, they don't get any XP even if they still have it with them. (But they might later on.) If they sell it, then they'll sell it according to its price if it wasn't magic but without an XP worth. If it takes some time to Identify it and the people doing so are not the exact same as the characters who initially looted it, I reward XP to those who were there to initially loot it only, and with the same split as if the other original looters were also there to receive it. I think XP for magic items are balanced in that there's always the risk that a magic item will not be recognized as such and be entirely overlooked. I'm not particularly afraid of giving something too powerful for the party because it still has to fit within my XP Budget. If a single magic item takes most of my XP budget, or so much that there's little left for monsters, traps and regular treasure, then I know it's too powerful.
Story/Goals: I used to give XP for those things, but don't anymore. In the end, D&D is about fighting monsters and looting treasure. Those ARE the story and goals. Sure, it might be nice to do a session at the royal court making contacts or solving mysteries, but those are very low-risk and are rewarded by a growing character knowledge of the setting and the possible gain of new contacts and allies, or at least knowing who's the enemy. Or maybe they aren't low-risk if assassins and other dangers do show up during those moments, but then that's what the XP rewards from my list are for! (Avoiding a poisoned drink because you smelled it in time would be discovering and avoiding a Trap in game terms, for example.)
Let's use the Death Star as an example.
Surely blowing up the Death Star was a huge moment in the story of the characters and their entire setting! It SHOULD be worth lots of XP, right??? Well, I would say that in itself, blowing up the Death Star was maybe worth the same as a very, very low-level trap, and only because it did require a skill roll from Luke to shoot and not miss at a crucial moment.
Blasphemy? Not so. I would say that the Death Star RUN, the assault itself, was worth LOTS of XP! Along the way, there were plenty of Traps (all those cannons shooting at them) and Monsters (The enemy Tie Fighters, one of them being particularly dangerous, the one piloted by Darth Vader!) The dangerous environment that was the trench is also a trap in itself, it could even be argued that it was worth XP for every round inside it! One wrong skill roll while dodging an attack while in there and you hit the side of the trench or a nearby ally! So in the end, attacking the Death Star and blowing it up was worth lots of XP, but it was all of its elements that made it worth so much, not the single act of blowing it up. Succeeding in the mission and surviving it doesn't mean you get extra XP for the goal, it means you get to receive your XP for all that happened while in that 'dungeon'.
As a side-note, I use the treasure listings of monsters from the books mostly as a guideline. Sometimes I use them, sometimes I ignore them. In any case, in the end it has to fit with my XP budget.
Next, an update on how I handle XP Budget when preparing a game!