The Longest Day

Macros with coordinates for TomTom users.
Its good to have all in one place.
(edit: added faction side for Kalimdor & Eastern Kingdoms quests)

Every player must finish following dailys:

1. 
   
2. Azeroth Horda/Aliance
3. 
   
4. Outland
5. 
   
6. Northrend
7. 
   
8. Cataclysm
9. 
   
10. Grand Master Trixxy
11. 
    
12. Grand Master Lydia Accoste
13. 
    
14. Pandaria
15. 
    
16. Pandaren Spirits
17. 
    
18. Beasts of Fable (books)
19. 
    

Side

A
A
A
A
A
A

A
A
A
A
A
AH
AH

Eastern Kingdoms

/way The Cape of Stranglethorn 51.2 73.6 Bill
/way The Hinterlands 62.99 54.57 David
/way Eastern Plaguelands 67 52.4 Deiza
/way Burning Steppes 25.6 47.6 Durin
/way Duskwood 20.2 44.2 Eric
/way Elwynn Forest 41.6 83.6 Julia

/way Searing Gorge 35.6 27.8 Kortas
/way Redridge Mountains 33.2 52.6 Lind
/way Westfall 60.8 18.6 Mac
/way Northern Stranglethorn 46 40.4 Lis
/way Swamp of Sorrows 76.6 41.6 Eve
/way Twilight Highlands 56.6 56.8 Goz
/way Deadwind Pass 40.2 76.6 Lyd

Side

H
H
H
H
H
H
H

H
H
H
H
AH
AH
AH

Kalimdor

/way Thousand Needles 31.8 32.8 Kela
/way Feralas 59.6 49.6 Gluk
/way Dustwallow Marsh 53.8 74.8 Grazz
/way Southern Barrens 39.6 79.2 Cass
/way Desolace 57.2 45.8 Merda
/way Stonetalon Mountains 59.6 71.6 Zonya
/way Northern Barrens 58.6 53 Dagra

/way Durotar 44 28.8 Zunta
/way Ashenvale 20.2 29.6 Analynn
/way Felwood 40 56.6 Zoltan
/way Moonglade 46 60.6 Elena
/way Winterspring 65.6 64.6 Trixx
/way Uldum 56.6 41.8 Obalis
/way Mount Hyjal 61.4 32.8 Brok

Icecrown

/way Icecrown 77.4 19.6 Payne
/way Crystalsong Forest 50.2 59 Jacob
/way Zul'Drak 13.2 66.8 Gutretch
/way Dragonblight 59 77 Okrut
/way Howling Fjord 28.6 33.8 Beegle

Outland & Deepholm

/way Shadowmoon Valley 31 41.4 Antari
/way Shattrath City 59.4 69.8 Morulu
/way Nagrand 61 49.4 Narrok
/way Hellfire Peninsula 64.4 49.2 Nicki
/way Zangarmarsh 17.2 50.6 Ras'an
/way Deepholm 49.8 57 Bordin

Pandaria (Spirits, Tamers & Books)

/way Vale of Eternal Blossoms 67.6 40.8 Aki
/way Kun-Lai Summit 35.8 73.6 Yon
/way Valley of the Four Winds 46 43.6 Nishi
/way The Jade Forest 48 54 Hyuna
/way Krasarang Wilds 62.2 45.8 Mo'ruk
/way Townlong Steppes 36.2 52.2 Zusshi

/way Dread Wastes 55 37.6 Shu
/way Townlong Steppes 57 42.2 Burning
/way Dread Wastes 61.2 87.6 Flowing
/way Kun-Lai Summit 64.8 93.6 Thundering
/way The Jade Forest 28.8 36 Whispering

Book I
/way Jade Forest 57.04 29.12 Nitun
/way Jade Forest 48.42 70.96 Ka'wi
/way Kun-Lai Summit 67.87 84.69 Ryga
/way Kun-Lai Summit 35.18 56.17 Kafi

Book II
/way Valley of the Four Winds 40.54 43.67 Yi
/way Valley of the Four Winds 25.29 78.54 Grey
/way Krasarang Wilds 36.23 37.34 Xi

Book III
/way Townlong Steppes 72.26 79.78 Ti'un
/way Vale of Eternal Blossoms 11 71 No-No
/way Dread Wastes 26.18 50.27 Gorespine

Just a "little" summary of what is needed in which area:

Kalimdor:
- Winterspring: Grand Master Trixxy
- Mount Hyjal: Brok
- Durotar: Zunta
- Northern Barrens: Dagra the Fierce
- Uldum: Grand Master Obalis
- Desolace: Merda Stronghoof
- Theramore's Fall: Grazzle the Great
- Stonetalon Mountains: Zonya the Sadist
- Southern Barrens: Cassandra Kaboom
- Thousand Needles: Kela Grimtotem
- Felwood: Zoltan
- Feralas: Traitor Gluk
- Moonglade: Elena Flutterfly
- Ashenvale: Analynn

Eastern Kingdoms:
- Elwynn Forest: Julia Stevens
- Westfall: Old MacDonald
- Cape of Stranglethorn: Bill Buckler
- Hinterlands: David Kosse
- Eastern Plaguelands: Deiza Plaguehorn
- Searing Gorge: Kortas Darkhammer
- Swamp of Sorrows: Everessa
- Burning Steppes: Durin Darkhammer
- Deadwind Pass: Grand Master Lydia Accoste
- Redridge Mountains: Lindsay
- Twilight Highlands: Goz Banefury
- Duskwood: Eric Davidson
- Northern Stranglethorn: Steven Lisbane

Outland:
- Hellfire Peninsula: Nicki Tinytech
- Zangarmarsh: Ras'an
- Shattrath: Morulu The Elder
- Nagrand: Narrok
- Shadowmoon Valley: Grand Master Antari

Northrend:
- Howling Fjord: Beegle Blastfuse
- Dragonblight: Okrut Dragonwaste
- Icecrown: Grand Master Payne
- Crystalsong Forest: Nearly Headless Jacob
- Zul'drak: Gutretch

Other (Cataclysm):
- Deepholm: Bordin Steadyfist

Pandaria:
- Jade Forest: Grand Master Hyuna, Whispering Pandaren Spirit
- Beasts of Fable: Book I, Book II, Book III,
- Townlong Steppes: Burning Pandaren Spirit, Grand Master Zusshi
- Krasarang Wilds: Grand Master Mo'ruk
- Dread Wastes: Grand Master Shu, Flowing Pandaren Spirit
- Valley of the Four Winds: Grand Master Nishi
- Vale of Eternal Blossoms: Thundering Pandaren Spirit, Grand Master Aki
- Kun'Lai Summit: Grand Master Yon

I'd also like to mention these are the ones wowhead lists, but they didn't match my achievement requirements. Elena Flutterfly for example was not on my achievement list. Cannot find any other examples at the moment, and I couldn't find any I had but wowhead didn't, either, though. Sorry for the long post, hope it helps!

Doing all 41 of the necessary quests in one day (others have noted that you don't have to do both Horde and Alliance) is going to be somewhat of a mission. Even if it takes 6 minutes per battle (including travel time) that is close to 4 hours.

I have a suggestion that can make this a bit more manageable: Do a bunch of quests before the day you want to complete the achievement but don't hand them in. Unfortunately there is still your quest log limit of 25 quests, and there are probably a few quests you want to keep in your log (like Wrathion's Legendary quest), but it should be possible to clear up 20+ quest slots.

First up, defeat all the beasts of fable. They will easily take the longest, and all three quests can be turned in at one spot. This alone will save you close to an hour.

Then choose the hardest pet battles remaining, since those are going to take the longest (especially if you suffer a defeat or 2). So that would be the four Spirit Tamers, The 7 Pandaria Tamers, and then a combination of Northrend/Cataclysm trainers. You won't be able to cut down on travel time, because you'll still have to go and visit all of them on the day to turn in your completed quests but at 3-4 minutes a fight (assuming no defeats) this is still another hour saved.

When it comes to the day you want to go for the achievement, do the dailies you don't already have in your log first and starting with the easiest. Turn in the pre-completed quests last. That way, if something happens and you are unable to get through the 20 or so battles you need to do, you won't have to repeat all the pre-completed quests too.

A final hint - for far out of the way tamers (for example Winterspring), send an alt there in advance and leave it logged out at the quest giver. That way you can cut down on your travelling time. If you have several alts doing this it can add up to a significant time saving of 5 or so minutes per alt.

All in all, by doing a bit of the workload in advance and spreading the effort over a few days, you can almost halve the time you will need to budget for the big day.

edit: I can confirm that this method does in fact work by turning in for a battle I completed last week and had sitting, completed in my log. Turning in the quest is indeed what triggers the achievement progress. The battles themselves can be done in advance :)