Stick with your initial choice of Engineering.
Personally, I had a lot of problems leveling my pally - just couldn't survive encounters with even or higher level mobs and had to resort to picking on lower level stuff and leveling slow.
Then I took up engineering - OMFG! - the dps increase and survivability improvement was spectacular!!!!!!!!!
The explosives not only give a pally additional AOE damage, but more importantly, AOE stun for CC.
The target dummies will distract adds long enough to finish off whatever you're currently fighing, thus more CC.
The invisibility trinket has come in handy a boat load of times.
The parchute cloak is a great peice of gear for tank/ret pally and the feather fall has its uses.
As a goblin engineer, I get rocket launcher and dragon gun, two items that help imensly (especially the dragon gun - beautiful AOE).
And as an added bonus you get the epic helms.