Below I have posted screenshots of every guild base I have knowledge of. If you know of any other guild bases feel free to comment below and I will either go there or if you are in the guild and can invite me then feel free to DM me on discord at Avery#1009 and I can get onto my alt to teleport there via the guild tabard.
I have also started putting guild tabards of each guild below the locations of the guilds.
Macrochelys
Kalimdor>Azshara
Coords: 28.5, 70.9
Has a flying mount in the base that lasts for approximately 45 seconds.
The Emerald Dream
Kalimdor>Ashenvale
Coords: 93.9, 25.5
Has a flying mount in the base that lasts for approximately 45 seconds.
Hard Chores
Kalimdor>Desolace
Coords: 31.1, 87.6
Has a flying mount in the base that lasts for approximately 45 seconds.
Traveler
Kalimdor>Feralas
Coords: 44.3, 16.1
Has a flying mount in the base that lasts for approximately 45 seconds.
Farmers Market
Kalimdor>Un'Goro Crater
Coords: 38.9, 11.4
Has a flying mount in the base that lasts for approximately 45 seconds.
Hawks Talon
Eastern Kingdoms>Wetlands
Coords: 48.7, 61.8
Has a flying mount in the base that lasts for approximately 45 seconds.
Rush and Attack
Kalimdor>Darkshore
Coords: 68.5, 18.4
Has a flying mount in the base that lasts for approximately 45 seconds.
Squad
Kalimdor>Feralas
Coords: 49.9, 57.1
Has a flying mount in the base that lasts for approximately 45 seconds.
Northshire Renegades
Eastern Kingdoms>Elwynn Forest
Coords: 59.1. 28.7
Has a flying mount in the base that lasts for approximately 45 seconds.
For clarity the map marker is where the base is.
The Blackwing Guard
Eastern Kingdoms>Burning Steppes
Coords: 18.4, 65.9
Has a flying mount south of the base that lasts for approximately 45 seconds.
Thunderhorn Clan
Kalimdor>Thousand Needles
Coords: 28.1, 25.1
Has a flying mount south of the base that lasts for approximately 45 seconds.
For clarity the blue square is where the base is.
Wolfskull Clan
Kalimdor>Ashenvale
Coords: 72.9, 55.8
Redwater Syndicate
Eastern Kingdoms>Stormwind
Coords: 48.6, 72.7
Guild no longer exists. So cannot get the tabard design
Nephilim
Eastern Kingdoms>The Hinterlands
Coords: 90, 24.7
Conquistadores
Kalimdor>The Barrens
Get Rich Or Die Grinding
Kalimdor>Un'Goro Crater
Coords: 76.4, 66.6
The Scarlet Crusade
Eartern Kingdoms>Tirisfal Glades
East Oceanic Trading Co
Kalimdor>Tanaris
Coords: 66.9, 11.3
Golden Moon
Kalimdor>The Barrens
Coords: 64.5, 34
Blacktooth Grin
Eastern Kingdoms>Swamp of Sorrows
Coords: 50.7, 46.2
Thunder Ale Brewing Co
Eastern Kingdoms>Arathi Highlands
Coords: 91.5, 70.9
The Crusade
Eastern Kingdoms>Eastern Plaguelands
Coords: 20.8, 83.6
Rats
Kalimdor>Thousand Needles
Coords: 81.6, 53.6
The Lions Pride Legion
Eastern Kingdoms>Duskwood
Coords: 32.2, 46.7
Templarios
Eastern Kingdoms>Alterac Mountains
Coords: 80.3, 51.3
The Scourge
Eastern Kingdoms>Tirisfal Glades
Coords: 85.5, 55.4
Southfury Trading Co
Kalimdor>Barrens
Coords: 61, 23.4
Hard Knocks Society
Kalimdor>Tanaris
Coords: 57.3, 21.6
Schmetterlingsbrigade
Kalimdor>Tanaris
Coords: The coords are off the screen. If you are using a coordinate addon I would suggest looking at Kalimdor map and getting to the coords listed here: 58.7, 98.7
You can get here with shaman water walking or completing the Love Song for Narain quest chain from the Shifting Sands quest line. Their base is at the South Seas Islands.
The Silver Crusade
Eastern Kingdoms>Hillsbrad Foothills
Coords: 42.1, 53
Murky Waters
Eastern Kingdoms>Hillsbrad Foothills
Coords: 14, 48.2
Heirs of Quel'thalas
Eastern Kingdoms>Loch Modan
Coords: 58.1, 74.7
School of the Dragonhawk
Kalimdor>Winterspring
Coords: 49.2, 32.5
Their base is in a cave. The mouth of the cave looks like a nightelf enterance to a cave. If you go down the winding passages you will find a banker with <School of the Dragonhawk> as his title.
Ered Ruin
Kalimdor>Ashenvale
Coords: 79.2, 80.7
Thalassian Alliance
Eastern Kingdoms>Stormwind
Coords: 37.2, 74.4
Warsong Outriders
Kalimdor>The Barrens
Coords: 47.6, 10.0
