I'm thinking about buying a portable gaming system for business trips.

if you can wait a few months, and like classic (emulated) games, take a look at http://www.openpandora.org/index.php?option=com_content&view=article&id=90&Itemid=10&lang=en... slightly larger than a DS, full gaming controls (a/b/x/y, d-pad, 2 analogue sticks, shoulder buttons) plus a qwerty keyboard, emulates old arcade games up to PS1, and runs a Linux desktop for web/email/etc... it's been quite a wait for bulk shipping to get started, but production finally seems to be on track...

The DS was my answer hands-down, until you mentioned you already had one and got rid of it. And the bias towards action games, which I don't think the DS is all that strong on. That's probably the one category that the PSP wins. Metal Gear Solid: Peace Walker, God of War: Ghost of Sparta, several GTA iterations (though to be fair Chinatown Wars is on the DS). They're both solid systems. Head over to metacritic or find a few "top __ games" lists and just make a tally of stuff you want to play. *goes back to Picross 3D which is the best game ever and everyone should play it*

If you don't have to change hotels during your trip, you might want to consider just bringing your XBox or buying another one to use when you travel. That way you'd be able to play games you already own, and play them on your home system as well. This, of course, doesn't do anything to fill your time in the airport or on planes, but I thought I'd toss it out there in case you hadn't considered it. My brother travels multiple times a year for business and does this. With many hotels having front inputs on their tvs, it's really simple to set up and take down. He does stay at the same hotel each time, so he knows he'll always be able to plug his console in. If you're staying in different hotels every time and don't know what their standard tvs are like, this might not work as well.

Sorry, should have said: Carrying the Xbox with me is not gonna work. Too big, and much too heavy (For the one-week trips, I usually live out of a carryon), and my hotels do vary and frequently have awful ancient TVs. Plus, my trips are frequently international and I do personal travel afterwards; keeping to a minimum the amount of weight I haul through the streets of a city to my next hostel is important.

You might want to look at an iPad. I've been on a week-long trip to India and the iPad was great for watching movies & shows as well as playing games. The battery life is pretty decent too. I find the PSP and DS screens kind of small for long playing sessions.

DSi for game variety and the lack of update nonsense. I'm with IndigoRain though, keep your eyeballs peeled and you can get both of them refurbished for the price of one. The DSi is super duper travel-friendly, I've found. The battery lasts forever, the flip-top keeps the screen safe, and the whole form factor of the object makes it much easier to slip into a pocket or knock around in a bag without worrying. The little cartridges (or whatever they're called) are hard/impossible to break, as well. Do you play on portable consoles much? I find that my taste in genres varies on console format. For the big box consoles I like certain sorts of games, but for portables I like a lot of different ones I normally wouldn't enjoy. So, don't limit yourself in terms of genre.

I have both and don't really use either. They're both too big and feature ugly 3D graphics (in my opinion). I love love love my http://en.wikipedia.org/wiki/Gameboy_micro, which is wonderful for its cheap collection of 2D RPGs (Final Fantasy), Action-Adventure games (Zeldas), Platformers (Mario), and Metroidvanias (Metroid/Castlevania). Also, it's not embarrassing for me to use in public. It features vastly different games from the new home consoles, which is great for me as well.

I bought a psp3000 series a few years back and modded it straight away. I find that I can't stand to play it for ANY length of time before it seriously hurts my fingers. I played God of War something something Wrath to completion, and I played a couple others like Ace Combat, and whatever I'd downloaded, but nothing else to completion. I've considered picking up a DS for the lady, she prefers Nintendo style games, and then modding that---but haven't so far because nothing absolutely jumps out at me. Really, I chimed in to say that the PSP form factor SUCKS, and it will hurt you. OTOH, you get skype and really very rich colors and graphics. It really looks very nice.

I have a DS, but the only time I've taken it out since I got my iPhone is to play the Professor Layton games. (Which I love and definitely recommend if you choose a DS.) So I guess I'm here to say, "Maybe take a second look at your iPhone?" New games are coming out every day, and game manufacturers are getting better and better at making the most of the touch-screen controls. Since you're specifically looking for long games, some recs: The iPhone is awesome for adventure games, and a lot of classics have been ported, like The Curse of Monkey Island, Broken Sword, and the sequels to each. You could probably spend your 60 hours of downtime just on those four games. You could also try a more modern twist on the adventure game like Phoenix Wright. For RPGs, Aralon. It's not perfect but it's good fun, especially if you've played games like Wow. I've also heard good things about Dungeon Defenders, which is an RPG/Tower Defence hybrid. Lego Harry Potter has at least twenty hours of core gameplay, and then much more if you go back with your unlocked characters to find every hat and token. Finally, some puzzle games I've spent hours playing: Aqueduct, Helsing's Fire, Trainyard. Several of these games are also available on DS. (Broken Sword, Lego HP, Phoenix.) It's my understanding that the iPhone versions are exactly the same, and as a bonus, they tend to cost around 10-20% of the price of the DS versions.