I tanked Deadmines with sounding success. Made lvl 22, and got Cookie's Tenderizer. I liked it very much, provided not only loot, but also lot of XP, so instancing is totally go for me.
However as a businessmen I'm hesitating to recommend it to others from the perspective of cost-effectivity. Since patch 2.3 the XP from quests increased a lot between level 20 and 40, therefore you can level quickly alone. Loot is not so valueable, since you can have plenty of green quests to do, if your gear is weak. Questing a sure method and depend only on you. Instancing depends on 5 people, 20% idiot content can turn it into a wipefest. I am a prot paladin, so I'm a tank. I mark the mobs, I set the kill order therefore things can only go wrong if one is really sabotating. However if you are a DPS, and get a noob tank, or one who tanks on full fury/retri with a lowbie shield, things can get really nasty. So make your own call on instances.
I also managed to mine a lot in Deadmines, being the only miner. Later in Ironforge I bought iron ores to level mining to slvl 152 with smelting. It's green now and won't level more. Have to reach slvl 165 by mining nodes for steel smelting.
At the end of the day I have 142G. My enchanting material is still just partially sold and I also invested some gold in iron bars. I expect to sell them later.
I've also found a guide how to use Appraiser, the selling module of Auctioneer advanced. Wanted to write it myself but Og saved me from that.