All the Ace Attorney games are top notch, and since they all build upon each other, sequels tend to be much more fun. Additionally, since new mechanics are generally introduced with each subsequent game, you get quite a bit of fun out of each of them. Most Phoenix Wright fans would rank them in the following order: 3 (Trials and Tribulations), 1 (Ace Attorney), and 2 (Justice For All).
Because the fourth game stars a new protagonist and handles some mechanics differently, it tends to be hit or miss with fans. I personally thought it was great, and would put it
just slightly under PW1 in terms of quality, which might sound bad but actually is quite a compliment.
Hotel Dusk is really more of an interactive novel than a true adventure game - there's not many puzzles, not a huge inventory, etc. Really what you do is sort of guide the story along by walking around the hotel and talking to the various inhabitants. Yes, you can "lose," but it's few and far between. The strengths of the game are 1) the art, which is beautiful and anyone who says otherwise is a damned fool, 2) the music, which is jazzy and mellow, and 3) the characterization, since all of the characters feels like honest individuals. But again, there is very little "game" here, which creates another love-or-hate relationship. One last thing to mention is that it just got a reprint, which means this is basically your last chance to get it. I doubt we'll see a sequel...ever, but this game is definitely going to be hard to come by years from now.
I haven't tried much Trace Memory, but it's from the Hotel Dusk people. It seems that it is more of an honest puzzle/adventure game, but that most people who like it AND Hotel Dusk tend to say it is the inferior of the two. I need to go and play it.
Touch Detective....I've only started 1, and it has some serious appeal with funny dialogue and some unique art and characters. It's an actual adventure game and I could see it lasting a good while. Reviews complained that the puzzles were often highly illogical, so take that as you will.
Time Hollow has a thread
'round here. Most people in there are saying it is very good BUT it is extremely short, and that $30 for a 5 hour game might not be high on anyone's priorities.
You can also check out Insecticide. Here's a thread about adventure games, and I'm linking you to the last page with
my impressions. Basically it's "about a 7." The adventure portions work but aren't that long and don't come up as often as I would have liked. The action portions tend to be frustrating. You're better off trying this out on the PC, since it is available there also.
If you haven't tried it, Professor Layton and the Curious Village is
masterful and everyone should play it. Yes, it's basically a string of logic puzzles, but it wrapped up in the most amazing artwork and characters I've seen among portable games. It's an absolute gem and you should definitely play it. There should be two sequels coming stateside (I hope).
There's Jack Hunter (Jake Hunter?) but I don't know much about it. Seems like it's rather generic for an adventure game, or so I've heard.
An upcoming game will be Runaway: Dream of the Turtle, which is a port of a PC game that was released last year. This is a tough one to think about because I'm wondering how the port will be, which basically is me asking "Will the graphics take a hit and will all the voicework be included?" Overall the game is pretty good, but I'd want to see a review telling me what is/is not missing from the PC version. Additionally, this is the second game in the Runaway series, which kind of hurts the game since you really ought to play the first one to get a little more out of the second one. HOWEVER, this is not required, since the second game more or less functions as a story on its own. It does end on a cliffhanger, which means the next game in the series SHOULD clear everything up, but this too might hurt the DS version because there's no telling if they will port that as well.
Myst was released on the DS, but I heard from everyone that the port is very shoddy and should be ignored.
Secret Files Tunguska...I think it's good, but it's on the PC already and should be heading to the Wii as well, so I'm guessing you really only get the DS version if you absolutely must have portability.
There should be one called Ankh at some point. Don't know anything about it.
I think that's all I can think of for the time being. This genre is one of my favorites in all of gaming, so I hope I helped you out.