Im going to hong kong on the 25th of this month and I need a game cuz it's a really long ride.. im thinking about  Mario & Luigi: Bowsers inside story what do you guys think? 

or maybe GTA: Chinatown Wars? 

It depends on what you like and whether you want short bursts or in depth and long play.  I find strategy games my favourite diversion, such as Advance Wars.  Other than that, maybe an RPG like Chrono Trigger (or any of the multitude of RPG available).  What about Mario Kart? 
 
Don't forget to buy lots of cheap DS games whilst you are there [legitimate ones]  :-)

    If you don't mind a nice dose of crazy japanese the ace attorney series lasts a while and is a lot of fun.  My favorite portable series ever.

"     If you don't mind a nice dose of crazy japanese the ace attorney series lasts a while and is a lot of fun.  My favorite portable series ever. "

" Fire Emblem: Shadow Dragon "

Anything on the first part of this list, and any RPG throughout the list should serve you well

" Anything on the first part of this list, and any RPG throughout the list should serve you well "

Thanks! 

" Fire Emblem: Shadow Dragon "

I would get two games, one as a diversion and one for the long haul. Because if you nab up some long RPG and get your ass kicked, now you're just frustrated with nothing to do. I would consider the latest Castlevania game.

DEFINITELY mario and luigi.
i want that game.

Prof. Layton, both of them

Phantom Hourglass

Phantom Hourglass for a game with substance. 
N+ for a quick distraction game.  Maybe Geometry Wars instead.

I went to Oregon over the summer, and played Chinatown Wars on the plane. It was great. You can kill a lot of time selling drugs in that game.  
Although I'm sure a flight to Hong Kong will take much longer... I had a lot of fun with it... 
Which reminds me, I still need to beat that game. 
 
I'd recommend it, though there are longer games on the DS. I agree with pretty much any RPG would do the trick, and the DS has plenty of those.

" @oldschool: It was implied by my ignorance of your comment "

hmm im kinda interested in the latest castlevania... i have phantom hourglass 

Just stay up playing video games and sleep through the trip.

Professor Layton.

" I would get two games, one as a diversion and one for the long haul. Because if you nab up some long RPG and get your ass kicked, now you're just frustrated with nothing to do. I would consider the latest Castlevania game. "