Archaeology: Where to start

I've read some guides about Archaeology lately...
In case you didn't, I'll put here a bief synthesis:

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• Archaeology will be a secondary profession, i.e. everyone will be able to take it without having to remove any profession.
• With Archaeology you'll be able to get some vanity items (pets and mounts, but also other things) and some BoA weapons which requires lvl. 85 ( = not leveling weapons). Those prices will be divided in "races" on which you can investigate (horde and alliance can both research on every race).
• You won't get the same artifact twice, unless you have already discovered all artifacts that race could give you.
• Dig sites can be seen on you map, not your mini-map.
• Once you are in the zone which contains the dig sites, you have to search for the exact location using a surveying tool. Here you can find a good guide: http://www.youtube.com/watch?v=I7x3WGF4fX0
• First 100 skill points can come only from collecting the fragments, without completing the artifacts, so it's recommended that you keep the fragments you gather without completing any artifact until that point.

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Now, it's a good advice to try and focus on a single race even when leveling the skill... Focusing on a goal is always useful, especially if there is the risk to get bored.
The races you can research on are limited by your skill level in Archaeology. You won't be totally sure of which race a dig site belong until you have taken the fragments from the site.
However, sites of a race spawns in "coherent" places: you'll better look for Night Elves in Kalimdor and for dwarfs in the  Eastern Kingdoms.

From the beginning you will be able to do research on the races of the Eastern Kingdoms and Kalimdor :

• Night Elf 
• Troll 
• Dwarf 
• Fossil

Starting from skill level 300 you will be able to research in Outland:

• Draenei
• Orc

Then at skill level 375, Northrend:

• Vrykul
• Nerubian

And once you reach skill level 450 you'll unlock the last race, located in the Cataclysm Zones:

• Tol’vir

So, you'll start with plenty of option, let's see what the races of the "Old World" have to offer:

Night Elf:
[Tyrande's Favorite Doll] (BoA, requires level 85)
[Queen Azshara's Dressing Gown] (BoA, requires level 60)
[Bones of Transformation] (Transforms the user into a Naga for 20 seconds.)
[Wisp Amulet] (Transforms the user into a Wisp for 20 seconds.)

[Highborne Soul Mirror]
[Druid and Priest Statue Set]
[Kaldorei Wind Chimes]

Troll:
[Zin'rokh, Destroyer of Worlds] (BoA, requires level 85)

Dwarf:
[Staff of the Sorceror-Thane Thaurissan] (BoA, requires level 85)
[Clockwork Gnome] (BoP, pet)
[The Innkeeper's Daughter] Could be a second hearthstone (set on the same location of the first one), but it's not sure if it will share the cooldown with the normal hearthstone (thus becoming a substitute hearthstone with some flavor-text)
[Chalice of the Mountain Kings]

Fossil:
[Fossilized Raptor] (BoP, mount)
[Fossilized Hatchling] (BoP, pet)

It should be noted that you'll receive skill points for any artifact you solve, so you don't have to go to the outland once you hit 300. You can still remain in the old world, if you want to complete artifacts from one of these races. It also seems that the Night Elf, Troll, Dwarf and Fossil artifacts will need less fragment to be solved.

I think you should remain on these ones, specially if one of the ilvl 395 items that you can find is good for your class. As of now (everything can still change) the races from Outland and Northrend won't give you any useful-for-lvl-85 loot. Talking about changes, even the lists for the four starting races seems quite uneven... While I understand that "Fossil" could be just a "vanity item race", I'm not sure of why Night Elves get seven items and Trolls just one... So you should probably check again for changes when Cataclysm arrives.

 If you wish to continue your journey to the Outlands, you'll find:

Orc:
[Headdress of the First Shaman] (BoA, requires level 70)

Draenei:
[Arrival of the Naaru ]
[The Last Relic of Argus] (Teleports you to a random location)

And in Northrend:

Nerubian:
[Blessing of the Old God]
[Puzzle Box of Yogg-Saron]


Vrykul:
[Nifflevar Bearded Axe] (BoA, requires level 80)

Finally, in the "Cataclysm Zones" there will be just one race, the Tol'vir. The artifacts of this race are really the "final prices" of the profession, most of them BoA, with 3 ilvl 359 weapons.
Yes, unless you really devote a lot of time in farming this relics you may not get the weapon before the second tier of raids will be opened... But they're still BoA and can always be useful for an alt.

Tol'vir:
[Crawling Claw] (BoA, pet)
[Scepter of Azj'Aqir] (BoP, mount)
[Staff of Ammunae] (BoA, requires level 85)
[Pendant of the Scarab Storm] (BoA, vanity item)
[Ring of the Boy Emperor] (BoA, requires level 85)
[Scimitar of the Sirocco] (BoA, requires level 85)