On my seven characters, I ran thru the eastern entrance. I kept running until I broke aggro. There are very few solo quests in Giant Halls. As Guardian, you will have to in there at level 45 as part of one of your level 50 class quests. Guardian is the easiest class to operate in Giant Halls because you are a tuff as nails tank.
It is a lot more exciting with a squishy class like a Hunter. I done it with a Burglar, Captain, Champion, Lore Master, Guardian and Minstrel. Like I said there is not much to do in there as a solo player beyond the class quests. You need to bring friends. I used in a group of six to do the more difficult quests. Some people come back at 65+.
Unless stated otherwise, all content in this post is My Personal Opinion.