Elders of Northrend

Way Points with Elder Names
(Made from comments above, i just put elder names and paired it into macro sized chunks)

/way Storm Peaks 28.9 73.7 Elder Fargal
/way Storm Peaks 41 84 Elder Graymane
/way Storm Peaks 30 38 Elder Stonebeard
/way Storm Peaks 64 51 Elder Muraco
/way Zul'Drak 58 56 Elder Zim'Torga
/way Grizzly Hills 80 37.1 Elder Lunaro

/way Grizzly Hills 60.5 27.6 Elder Beldak
/way Grizzly Hills 64.1 47.0 Elder Whurain
/way Dragonblight 49 78 Elder Thorim
/way Dragonblight 35 48 Elder Skywarden
/way Dragonblight 29.9 56.1 Elder Morthie
/way Borean Tundra 33 34 Elder Nothal

/way Borean Tundra 57 43 Elder Arp
/way Borean Tundra 59.1 65.6 Elder Sardis
/way Borean Tundra 42.2 49.5 Elder Pamuya
/way Sholazar 49 63 Elder Sandrene
/way Sholazar 63 49 Elder Wanikaya
/way Wintergrasp 49.0 13.9 Elder Bluewolf

An accurate Horde specific guide:

Starting in Dalaran, check to see if horde control Wintergrasp. If they do, jump in the portal and then use the teleporter to enter the keep. Elder Bluehoof is inside. Once you have spoken to him jump back in the portal to Dalaran. If Wintergrasp is Alliance controlled, check again when you have worked your way through the list below.

1. 
   
2. Take a windrider to Bouldercrag's Refuge in Storm Peaks. Inside the Inn you'll find Elder Stonebeard. (Storm Peaks 31, 38)
3. 
   
4. Fly south to Elder Fargal just outside of Frosthold (Storm Peaks 30, 74)
5. 
   
6. Fly east-southeast K3. Elder Graymane is near the flightmaster (Storm Peaks 41, 85)
7. 
   
8. Take the windrider to Camp Tunka'Lo for Elder Muraco (Storm Peaks 65,51)
9. 
   
10. Take the windrider to Zim'Torga for Elder Tauros (Zul'Drak 59, 57)
11. 
    
12. Take the windrider to Camp Oneqwah and you'll find Elder Whurain (Grizzly Hills 65, 46)
13. 
    
14. Fly east-northeast to Elder Lunaro in Ruins of Tethys (Grizzly 81, 37)
15. 
    
16. Fly west-northwest to Elder Beldak just outside of Westfall Brigade Encampment (Grizzly 61, 28)
17. 
    
18. Fly back down to Camp Oneqwah and take the windrider to Moa'ki Harbor in Dragonblight. Elder Thoim is south, down by the dockmaster (Dragonblight 49, 78)
19. 
    
20. Take the Windrider to Agmar's Hammer. Elder Skywarden is on the southwest side (Dragonblight 35, 48)
21. 
    
22. Fly southwest to find Elder Morthi it Star's Rest (Dragonblight 30, 56)
23. 
    
24. Fly due west into Borean Tundra and head for the D.E.H.T.A.camp - near the T-junction in the road - to find Elder Arp (Borean Tundra 57, 44)
25. 
    
26. Fly due south to Valiance Keep. Elder Sardis is outside the walls on northwest side (Borean Tundra 59, 66)
27. 
    
28. Fly west-northwest to Warsong Hold. Pamuya the Elder is outside, on the northeast side (Borean Tundra 43, 50)
29. 
    
30. Fly Northwest to Coldarra. Elder Northal is inside the Transitus Shield (Borean Tundra 34, 34)
31. 
    
32. Take the windrider to River's Heart in Sholazar Basin to find Elder Sandrene by Lakeside Landing (Sholazar 50, 64)
33. 
    
34. Fly northeast to find Elder Wanikaya at the Rainspeaker Rapids (Sholazar 64, 49)
35. 
    

Edit: amended, thanks Puffmommy, algy and Bernok
Edit 2: fixed broken numbering

Elders of Northrend, including Northrend dungeons.
I start this guide in Borean Tundra as both the Zeppelin from Orgrimmar and the Boat from Stormwind has its destination here. For Alliance just follow the list, for Horde switch around 1.st and 2.nd. All Dungeons can be done on normal mode.

This guide assume that you have access to a flying mount.

Keep in mind, to complete Elders of the Dungeons Achievement you need to be at least level 77.
Also areas that spawns faction opposite guards will be max level guards.

Elder Sardis. Borean Tundra, Valiance Keep 59.09, 65.63
Elder Pamuya. Borean Tundra, Warsong Hold 42.94, 49.57
Elder Arp. Borean Tundra, D.E.H.T.A.camp 57.40, 43.72
Elder Northal. Borean Tundra, Coldarra 33.80, 34.37
Elder Igasho. Borean Tundra, The Nexus (Elders of the Dungeons) Just before Ormorok the Tree-Shaper. Minimum level 68, dungeon level 71-73
Elder Sandrene. Sholazar, River's Heart 49.77, 63.62
Elder Wanikaya. Sholazar, Rainspeaker Rapids 63.81, 49.01 Were Avatar of Freya stands
Elder Morthie. Dragonblight, Star's Rest 29.75, 55.92 (Spawns Alliance Guard)
Elder Thoim. Dragonblight, Moa'ki Harbor 48.77, 78.16
Elder Skywarden. Dragonblight, Agmar's Hammer 35.10, 48.34
Elder Nurgen. Dragonblight, Azjol-Nerub (Elders of the Dungeons) You need to clear the Dungeon to get out as the elder is past the drop down. Minimum level 69, dungeon level 72-74
Elder Bluewolf. Wintergrasp, Inside the Keep (If your Faction controls it)
Elder Graymane. Storm Peaks, K3 41.15, 84.74
Elder Fargal. Storm Peaks, Frosthold 28.89, 73.73
Elder Stonebeard. Storm Peaks, Bouldercrag's Refuge 31.26, 37.62
Elder Yurauk. Storm Peaks, The Halls of Stone (Elders of the Dungeons) About midt way up the Crystalline Quarry. Minimum level 74, dungeon level 77-78
Elder Muraco. Storm Peaks, Camp Tunka'Lo 64.60, 51.32
Elder Ohanzee. Zul'Drak, Gundrak (Elders of the Dungeons) Stand at the Drakkari Colossus. Minimum level 73, dungeon level 76-78
Elder Tauros. Zul'Drak, Zim'Torga 58.92, 55.98
Elder Kilias. Zul'Drak, Drak'Tharon Keep (Elders of the Dungeons) Stands at King Dred. Minimum level 71, dungeon level 74-76
Elder Beldak. Grizzly Hills, Westfall Brigade Encampment 60.56, 27.68 (Spawns Alliance Guard)
Elder Lunaro. Grizzly Hills, Ruins of Tethys 80.52, 37.10 At the east coast
Elder Whurain. Grizzly Hills, Camp Oneqwah 64.18, 46.99 (Spawns Horde Guard)
Elder Chogan'gada. Howling Fjord, Utgarde Pinnacle (Elders of the Dungeons) You need to get past Skadi. Minimum level 77, dungeon level 79-80
Elder Jarten. Howling Fjord, Utgarde Keep (Elders of the Dungeons) You need to get past the first boss. Minimum level 67, dungeon level 69-72

If you followed my guides for Kalimdor and Eastern Kingdoms you should then only need the following Elders

Elder Stonebrand. Deepholm, Temple of Earth at the entrance
Elder Deepforge. Deepholm, Stonehearth 28, 69
Elder Moonlance. Vashj'ir, Shimmering Expanse, Biel'aran Ridge 57, 86

Edit: Added Links and 3 more Elders
Edit: More accurate Locations, Corrected some false infomation
Edit: Added Links to Elders and maps
Edit: Added dungeon level requirements