You’ve got the obvious, Eversong and Ghostlands (Lorewise Ghostlands used to be called the Black Woods, before the Scourge came). You have some Reliquary stuff in Blasted Lands, but its not really lore stuff as such. Falcon’s Watch in Hellfire Peninsula is good fun, and you get the general lore vibe of -why-people flocked to Outlands by listening to the pilgrims in Thrallmar, the dialogue gets across the fact that these really were people looking for a better life, who had been utterly lied to, by the one person they should have been able to trust the most, their own crown prince…
Depending on your flavour of Blood Elf, you may find the Scryer/Shattrath stuff of interest, it certainly gives an idea as to how Kael’thas’ campaign started to unravel, once more and more people worked out what he was -actually- doing, and the lies he was feeding them. Depending on how far along you follow the Scryer stuff, then Shadowmoon Valley may be of interest, You get more Scryer stuff, then obviously you see the Blood Elf Demon Hunters being trained over by the Black Temple.
Lets not forget Terrokar forest, where there is a whole massive quest chain, leading up to that bete noir of the Warcraft World, our first introduction to the Mana Bomb.
Goes without saying that Tempest Keep, Magister’s Terrace and Sunwell Plateau are all pretty Belf-centric.
In Wrath its mainly all the Sunreaver stuff, If I remember rightly you first encounter an Image of Aethas in Dragonblight, and apart from a few brief interludes in Crystalsong forest, its pretty much all the Sunreaver stuff.
Mists of Pandaria is very good for Belf lore. The major questline for the Domination Point faction extensively involves Blood Elves, and neatly sets up the tragic events that occur later, with the Purge of Dalaran, as in, as the Horde player, you know Aethas is innocent, as the Alliance player, you are sure he is guilty. You get some major insights into the Sunreavers, and the High Elves in that. As in, No, not all Sunreavers are military or mages, some are just shopkeepers and civilians, and as for High Elves, oh my goodness they are not ‘the good guys’ at all, you basically play through some incredibly grim sectarian violence, which for once, the Blood Elves didn’t bring upon themselves. Following on from that is, as has been pointed out the Isle of Thunder. Oh this is good. This is a goldmine for Blood Elf info, We see the heavy hitters of the Blood Elves getting massively involved and getting their hands dirty, Lor’themar, Rommath, Halduron, Aethas, they’re all there. In particular Lor’themar firmly proves his bada$$ credentials. We see the return of the Mana Bombs, admittedly, this time as ‘Tactical’ Mana Bombs, so small ones, and we learn that Jaina and Vereesa are actually OK with Mana Bombs, as long as -they- are the ones using them. If you like Blood Elf stuff, Isle of Thunder is a -must see-.
In Warlords of Draenor, the Blood Elves play a fairly decent role as well, Liadrin is one of the first through the breach, and later it seems the Blood Elves have quite the sizeable army in Talador, where they are working alongside the native Draenei.
Legion doesn’t have much specific Blood Elf stuff to start with, although you do work with the Reliquary a fair bit if you have archaeology and take the quests, and then suddenly, in the latter stages of the Suramar story everything goes Elf-Tastic, the Battle of the Four Armies, Sin’dorei, Quel’dorei, Kaldorei, Shal’dorei, all get a massive slice of the pie, it looks pretty awesome to be honest, and does make you wonder what the species of Elves could have achieved had they not went their separate ways.
And that brings us to BfA.
For a start, -DO- the Heritage Armour quest. Even if you are never going to use it IC, do the quest, you get to play through the Scourge Invasion, see Quel’thalas as it was. Lor’themar is being utterly bada$$ again, Blood Knights don’t even exist yet, Liadrin is a Priestess, It takes you through Ghostlands, Eversong, Silvermoon, Quel’danas, right up to the Sunwell. It gives you a massive jolt of Blood Elf history and lore in one hefty package.
Apart from that, there isn’t much in BfA, however from the looks of things, our boy Lorthy is going to be a major player in 8.2, so we shall see…