If there's a game on the Nintendo DS that can (and will) make you miss your baths and is the epitome of the "just-one-more-turn" addiction normally found turned-based games on the PC, that game would be Puzzle Quest: Challenge of the Warlords.
Puzzle Quest plays a little bit like one of those Heroes of Might and Magic games on the PC. There's the game-world map whereby the hero moves around and there's also the hero's starting location, a city which can be upgraded with player-specific buildings.
The similarities with the HoMM end at combat. While there's also experience to be earned from combat, actual combat takes place as a Bejeweled game between the player and the AI. Where else can you say that you got pwned by a giant vampire bat in a game of Bejeweled?
Being an old title, Puzzle Quest would probably have dozens of reviews to its name, each would also be probably recommend that you get it. My sentiments exactly, having played the game. I got this game as a used copy a couple of weeks ago with Phoenix Wright: Ace Attorney for a paltry RM 90 or USD 28 for both!
If you need to get a new copy, the US version is available at Play-Asia for USD 24.90 (click here) whereas the Japanese import version, Simple DS Series Vol. 23: The Puzzle Quest: Agaria no Kishi (quite a mouthful) is also available at a cheaper price of USD 19.90 (click here).
P/S: Both titles are at bargain prices.