I personally wouldn't recommend Bloodmyst Isle. There's a ton of quests but a lot of those quests have absolutely horrible drop rates on their items. A lot of the quest mobs also have very slow and/or spread out spawns so if there's other people there you're gonna be waiting for respawns or spending a lot of time traveling between spawn areas quite a bit. Overall it's just an incredibly slow zone as far as EXP goes.
101+ At this point you'll start taking a penalty on quest/bonus objective experience for every level past 100. Treasures, however, remain worth their full value all the way through level 105, at which point they'll be worth something like 15% less, and then another 15% more when you ding 106. I recommend that you stop questing/gathering entirely, and collect all the treasures you can stomach, only avoiding any annoying to reach ones inside caves or behind elites/rares(where scaling does bizarro things).
The Alliance are able to unlock the void elves (exiled blood elves who can tap into shadow magic, trained by Alleria Windrunner after her experiences on Argus), Lightforged draenei (draenei members of the Army of the Light who fought the Legion on Argus), Dark Iron dwarves (fire-blooded cousins of the in-game dwarves of Ironforge), and Kul Tiran humans (larger, more heavyset versions of the in-game humans of Stormwind).
It's hard to step out of the shadow of Legion, which was utterly fantastic in almost every way, to enter an expansion where you get one item per boss in the last expansion because the rules have been changed to force more grinding, where you have to grind reputation in the old expansion that you probably skipped because rep grinds suck JUST to unlock allied races (who aren't fully unique races since they recycle old content such as animations), where questing has SOMEHOW become boring again and where your new abilities are given by items you'll swap out every level, meanwhile being only boring passive effects no one cares about.
REALMS Aerie Peak Aman'Thul Area 52 Arthas Baelgun Barthilas Blackrock Bleeding Hollow Burning Legion Cenarius Dalaran Darkspear Earthen Ring Emerald Dream Frostmourne Garona Garrosh Hyjal Illidan Kel'Thuzad Kil'jaeden Korgath Lightbringer Mal'Ganis Moon Guard Proudmoore Ravenholdt Sargeras Saurfang Shattered Hand Stormrage Stormreaver Thrall Tichondrius Turalyon Wyrmrest Accord Zul'jin Aegwynn, Bonechewer, Daggerspine, Gurubashi, and Hakkar Agamaggan, Archimonde, Jaedenar, and The Underbog Aggramar and Fizzcrank Akama, Dragonmaw, and Mug'thol Alleria and Khadgar Alexstrasza and Terokkar Altar of Storms, Anetheron, Magtheridon, and Ysondre Alterac Mountains, Balnazzar, Gorgonnash, The Forgotten Coast, and Warsong Andorhal, Scilla, Ursin, and Zuluhed Antonidas and Uldum Anub’arak, Chromaggus, Crushridge, Garithos, Nathrezim, and Smolderthorn Anvilmar and Undermine Arathor and Drenden Argent Dawn and The Scryers Arygos and Llane Auchindoun, Cho'gall, and Laughing Skull Azgalor, Azshara, Destromath, and Thunderlord Azjol-Nerub and Khaz Modan Azuremyst and Staghelm Baelgun and Doomhammer Black Dragonflight, Gul'dan, and Skullcrusher Blackhand and Galakrond Blackwater Raiders and Shadow Council Blackwing Lair, Dethecus, Detheroc, Haomarush, Lethon, and Shadowmoon Bladefist and Kul Tiras Blade's Edge and Thunderhorn Blood Furnace, Mannoroth, and Nazjatar Bloodhoof and Duskwood Bloodscalp, Boulderfist, Dunemaul, Maiev, and Stonemaul Borean Tundra and Shadowsong Bronzebeard and Shandris Burning Blade, Lightning's Blade, and Onyxia Caelestrasz and Nagrand Cairne and Perenolde Cenarion Circle and Sisters of Elune Coilfang, Dark Iron, Dalvengyr, and Demon Soul Dawnbringer and Madoran Darrowmere and Windrunner Dath'Remar and Khaz'goroth Deathwing, Executus, Kalecgos, and Shattered Halls Dentarg and Whisperwind Detheroc and Shadowmoon Draenor and Echo Isles Dragonblight and Fenris Draka and Suramar Drak’Tharon, Firetree, Malorne, Rivendare, Spirestone, and Stormscale Drak'thul and Skywall Dreadmaul and Thaurissan Durotan and Ysera Eitrigg and Shu'halo Eldre’Thalas and Korialstrasz Elune and Gilneas Eonar and Velen Eredar, Gorefiend, Spinebreaker, and Wildhammer Exodar and Medivh Farstriders, Silver Hand, and Thorium Brotherhood Feathermoon and Scarlet Crusade Frostmane, Ner'zhul, and Tortheldrin Frostwolf and Vashj Ghostlands and Kael'thas Gnomeregan and Moonrunner Greymane and Tanaris Grizzly Hills and Lothar Gundrak and Jubei'Thos Hellscream and Zangarmarsh Hydraxis and Terenas Icecrown and Malygos Kargath and Norgannon Kilrogg and Winterhoof Kirin Tor, Sentinels, and Steamwheedle Cartel Lightninghoof, Maelstrom, and The Venture Co Malfurion and Trollbane Misha and Rexxar Mok'Nathal and Silvermoon Muradin and Nordrassil Nazgrel, Nesingwary, and Vek'nilash Quel'dorei and Sen'jin Ravencrest and Uldaman Ravenholdt and Twisting Nether Runetotem and Uther
Zandalari troll (8.1.5) - "The Zandalari are a proud people whose origins date back to the early days of Azeroth's history. Their fierce warriors ride dinosaurs into battle, and they possess one of the most formidable naval fleets in the known world. But enemy attacks on their borders—as well as unrest within the king's council—have threatened the kingdom's foundations. By returning stability to Zandalar, the heroes of the Horde can gain a powerful new ally.."