Nintendo DS: Must have games?

[Snowhobbit]

I've recently begun working as a personal assistant, a work which essentially leaves me with long hours of nothing to do, we're talking 4-5 hours a day.
I've looked into things to do to kill time, and while books arn't a bad option I'm thinking of adding the DS to my repetoire of daily entertainment. The question is though, which games should I get? I've got my eyes on Zelda: Phantom Hourglass, Metriod Prime: Hunters and Dr. Kawashima's Brain Training, however I'm curious about any other good games on the market for the DS, I havn't kept track of recent releases in the past year or so
So I'm hoping all of you avid DS fans can fill me in on which games to get, and which games to avoid
Oh and an important factor is the ability to pause the game fairly quickly

[Fragony]

No real masterpieces yet but plenty of fun games. Can't go wrong with Zelda. Currently the best thing about the DS is that it can play GBA games.

[frogbeastegg]

From my own collection:

Magical Starsign - a nice, silly JRPG with DS interface.
Etrian Odyssey - very difficult old school PC style RPG based around exploring and mapping dungeons. Love it.
Freshly picked: Tingle’s rosy rupee land - not played it yet but it's so wierd it has to be good :p
Dragon Quest Heroes: Rocket Slime - even better if you've played any Dragon Quest games and can catch the in-jokes.
Pokémon Pearl - just because.
Castlevania: Dawn of sorrow - another good entry into Metroid style side of the series
Castlevania: Portrait of Ruin - ditto above
Kirby: Canvas Curse - inventive use of stylus control for platforming.
Mario Vs Donkey Kong 2: March of the Minis - it's Lemmings but better
New Super Mario Bros. - if you like platformers
Yoshi’s Island DS - ditto above. A much more difficult game despite the cute packaging
Phoenix Wright: Ace Attorney - think point and click reborn in an insane courtroom, right down to the funny dialogue a la Moneky Island
Phoenix Wright: Justice for All - slightly inferior sequel to the above. Play them in order for plot purposes.
Hotel Dusk: Room 215 - more point and click-esque goodness.
Meteos - puzzle game but not boring like Tetris :p
Picross DS - another puzzler.
Trauma Centre: Under the Knife - difficult. Inventive. Difficult!
Age of Empires DS - I found it better/less annoying than advance wars DS.
Anno 1701 - outstanding port of the recent(!) PC strategy game

[doc_bean]

Phoenix Wright: Ace Attorney, get it, love it, get Phoenix Wright: And Justice For All.

[Evil_Maniac From Mars]

I can't emphasize Castlevania enough. Fragony said there were no masterpieces for the DS - Castlevania is.

[Big King Sanctaphrax]

The two Castlevanias, Phantom Hourglass, Advance Wars: DS, Pokemon Pearl/Diamond, Hotel Dusk, The Phoenix Wrights, Mario Kart, New Super Mario Bros, Tetris DS (Can't have a handheld without Tetris).

[Snowhobbit]

Thanks for all the suggestions, sofar I've got Metroid, Zelda and Magical Starsign, which should still my needs for the moment, got plenty of titles on my "To buy" list, with Castelvania on the top of it. I've got a feeling I'll be able to squeeze lots and lots of hours of fun from this little machine