When to play Dungeon's?

My question is pretty simple;
When should I consider doing Dungeon's?
I just got GW;EN,so was wondering if I should begin playing Dungeons right now or once I beat GW;EN?
How much time does Dungeon take?
Is there any "popular" dungeon,oh and "useless" dungeon(like not worth the time)
Final question =P
With GW;EN,I got this map with all the Dungeons,I noticed that there's a Dungeon near Silfhalla,weird thing is that I went to the area and didnt see any Dungeon Gate,how come?

-Kyo!

The time to beat a dungeon varies. Some if not all of them (I can't remember) req-s somekind of EotN primary quest to be done.
You gotta be extremely lucky to get a rarer item from the endchest (IMHO). For the legendary master of north you must beat all the dungeons twice (1*NM 1*HM).
To sum all up, you should _consider_ doing dungeons when you are finished with everything or you're going for the title.

i would do EOTN in this order, but its all up to you

1) do all primary quests/missions, and finish the storyline. turn in your first book for vanguard faction

2) get rank 5 in all 4 factions, by mapping the zones while vanqhishing. also while you do this, finish all the quests to get all pve skills

3) all NM dungeons

dungeons are long, and some of them very difficult. plus, a lot of pve skills will come in handy, like light of deldrimor

Just make sure to pick up a Dungeon Book from the Herald in Eye of the North outpost. The completed books can be turned in for rank points.

Sifhalla, go out western gate, go west and there is a dungeon. Go out east gate, go north and there is a dungeon.

Check the locations on the wiki at http://wiki.guildwars.com/wiki/Dungeon

I agree with The Red Messenger about beating the game before doing any dungeons. Besides the fact you will have gained higher ranks in titles by then and one hero book to turn in, you will have also gained more heroes, money, and skills by that time. Most likely, you will also become a better player after playing through EoTN, assuming you don't get help from people everytime. I quickly started EoTN right after getting Prophecies and it was a tough learning curve, but now I can breeze right through it in a few hours and wonder how I ever had so much trouble.
I wouldn't vanquish any of the areas now just for points though. I left vanquishing for double points weekends to get two birds with one stone. I would however do all of the normal quests just to get the skills which can make the game a lot easier.
After you have all the skills, try out normal mode dungeons. Take into account this far into the game most dungeon rewards are useless. Almost no one buys them anymore. Goodluck.
Legendary Master of the North signing out

Personally I'm of the mind that you do dungeons when you feel like doing them.

Yes they'll be that bit easier if you've progressed further in the game, since you'll have more heroes, picked up useful PVP skills (not just Ursan) and have the rank to boost their output. However if you can get to the dungeon entrence, their's nothing to stop you picking up the dungeon's quest and having a go.

I cleared Sepulchre of Dragrimmar and Frostmaw's Burrows (although the latter with a load of DP) before I'd left Norn lands

How long does a dungeon take... Depends on the dungeon, how many levels it has and how well you do. Some are single level, some 3, some are 5 level, some are elite that you have to have finished the game to access.

They take a while to do. It's not like the quick 20-25 minute jaunt of the missions throughout the game, for the most part. The more popular ones are those that open onto, or very near to an outpost

1. Do the dungeons whenever you darn well feel like it. I don't think you have to finish the main questline first, but it is true that most of the dungeons are harder than anything in the main questline.

2. Time varies. Sepulcher can be completed in less than a half hour; Frostmaw may well take 2 hours on your first trip. (It gets faster once you learn the maps and the mobs.)

3. None of the dungeons are "worth it" in terms of the ratio of reward to time spent. Farming is way more profitable. Unless you actually enjoy playing the dungeon (or you really want the title), there's no reason to do any of them.

4. Th cave outside of Sifhalla is a little twisty-turny, but the entrance is there alright. Use your U-map.