Even when WoW was in its early days Gold Ore and bars were never worth much. Somehow an entire bar of gold was made to be worth less than a single gold coin. The Silver Ore was actually worth more because it was used in crafting recipes. Those were the old days though. Now players only need to worry about Saronite and Titanium, the two end game ores of WotLK... so far. Any possible future ore will most likely only drop inside raid instances.
Saronite, the strange ore that supposedly drives those who mine it crazy... If you believe some of the story lines in Howling Fjord, Borean Tundra, and Zul'Drak. A green clunky looking substance, it is found in player usable form only near the end of Zul'Drak. Previous forms of Saronite in the game are all related to quests. Supposedly the entire Wrath Gate, that giant metal wall blocking off the path between Northern Dragonblight and Icecrown, is crafted out of the stuff. Maybe it turns black once its forged, or maybe he painted it.
Saronite is only found in four of the zones in Northrend: Icecrown, Sholazar Basin, The Storm Peaks, and Wintergrasp. If you don't have an epic mount already, trying to mine up the gold for one is going to be painful, just because of all the players with epic fliers that will be stealing your nodes. Sholazar Basin is the go to spot for Saronite. While it doesn't have the highest number of node spawns, they are concentrated enough that a player will never find themselves in dead space. In other words, in Sholazar Basin pretty much wherever a player flies there is a node spawn. In Icecrown or Storm Peaks there are gaps of area that are empty to nodes which a player must fly across in order to reach a new section of them, since all the nodes where they were are currently respawning.
Icecrown and The Storm Peaks are also decent places to farm Saronite. As just mentioned, there are gaps between banks of nodes, and so farming anywhere but Sholazar Basin can feel as if you spend more time traveling from each bank of spawns than you do actually mining anything. Sholazar has two other major benefits over the other two zones for farming as well. Because it is a low level zone, a level 80 can mine and never get stuck in combat with a mob while someone comes and steals their node. Also, there are no Saronite spawns inside of caves in Sholazar, while in Icecrown and The Storm Peaks there are, which induces a lot of unnecessary downtime. The best thing to be said about Icecrown and The Storm Peaks for Saronite farming is that there will not be as many players there, and so hopefully you will come across a lot of nodes.
Rich Saronite works the same way that Rich Adamantite did in TBC; you get more bang for your buck off of a single node. It's a rare spawn off of the normal Saronite nodes, and so you can't really farm them. The other end game ore, Titanium, is also a rare spawn off of Saronite nodes. Titanium cannot be prospected, it is a material purely meant for crafting. It's still worth more a stack than Saronite just because of its rarity though, and as a miner you can easily craft a new Titansteel Bar whenever the cool down is up for a nice little profit.
There's only really one thing to do with Saronite. Prospect it. Selling the ore to a jewelcrafter in order for them to prospect is throwing money away. While the best option is to be a jewelcrafter yourself, or have a character that is one, a friend who doesn't mind prospecting for you will suffice. The ore itself is incredibly cheap, because of Sholazar Basin really, since it's so easy to farm. While most of the other prices have gone up since TBC the price on ore has actually dropped. Even if you have a friend prospect you might not make top dollar. Since the raw gems generally sell for a good bit less than the cut ones. If you're a blacksmith you can sell crafted pieces, Eternal Belt Buckles are a cash cow depending on your server, but prospecting is still the better way to go. Overall, unless coupled with jewelcrafting, mining is no longer the best option for making money.
Flying in Circles
The best way to mine ore is to fly circuits. Because ore nodes spawn in banks, it's very rare to find multiple nodes clustered together. Sholazar Basin has the easiest circuits of them all. Since the entire area is basically just a hole in the ground, and the zone is circular in nature. The most popular route to take is to just fly along the outside of the zone, near where the cliffs are. There are a large number of node spawns that appear on these cliffs. The only place you don't follow the walls of the basic is where it turns to snow in the North-east section called The Avalanche. You should instead skirt the edge of the snow, as it holds a few spots for ore, while the snowed area itself has few node spawns and a whole lot of mobs, some elite, which you cannot solo since they are part of a quest. The second route to follow in Sholazar is an inner circle. There are five pillars in the zone that make up a rough circle, and by following the outside path around all five of the pillars is another good way to get ore. Other routes can be made up, such as ones that crisscross the entire zone, but the nodes are concentrated along the outside and around the pillars, so those are the two best options.
The next best place to mine the end game ores is Icecrown. Icecrown is a much larger zone than Sholazar Basin. Putting together a proper route can be a scattered affair as the banks of ore are rather spread out. Another problem is that a good portion of the zone is flat ground that is teeming with hundreds of mobs that respawn rather fast. For some reason there are nodes there, perhaps to trick wary travelers into attempting to mine them and then the scourge kills them. The towering metal structures don't help much either, or the mountains, since you're either flying too high, or too low, and rather than covering real ground it's a lot of vertical movement just to get around. The best route for this zone is a horseshoe shape. With Ymirheim as the center of the horseshoe, and Ice Crown Citadel as the gap between the two ends. Flying first along the outside of the horseshoe, and then when coming back flying on the inside. Another option is to allow a vertical split down the center of the map and to just fly circles either on the east side or the west side. Any combination of routes can be used really, and in some places you may want to double back in order to sweep along two areas that are right next to each other. Flying to the other side of the mountains trying to look for nodes is not a good idea, and you should always stay more towards the center edge of the mountains then going up into them.
You really don't ever want to mine seriously in The Storm Peaks. The ore banks are very spread out, the zone is huge, and many of the nodes when you do find them will be inside a cave or surrounded by mobs. The only good reason to look for ore here is because you feel the other two spots are way over worked, or because you are mainly looking for the Time Lost Proto-Drake rare mount, and you need something to do while you spam trying to target it. There is no good path to take, except one that doubles back on itself a good amount.