Need a new questline

I am a level 40 Blood Elf. SO far I have been doing minor quests and dungeons since the long (and fun) forsaken quest-line. I am wondering if there are any nice, long quest lines that are full of interesting lore similar to the forsaken quest line near or at my lvl.

The Forsaken quest line is something special!

I would advise you to check out Eastern Plaguelands, level 40-45. The Caravan quest chain is quite fantastic. It starts near the bridge between the Western and Eastern Plaguelands.

As a second choice consider Thousand Needles, level 40-45. You'll be collecting ingredients to resurrect a pirate troll and reunite him with his wife. It ends with you confronting Magatha the hag, who poisoned Garrosh' weapon in his duel with Cairne Bloodhoof. To top it off, Thousand Needles is a beautiful zone.

The easiest way to find a new, level appropriate quest area is to check out the Hero's Call / Warchief's Command Board in your favorite major city.

These will always provide level appropriate "breadcrumb" quests that can lead you in to new zones with their own discrete storylines.