I was afraid this would be the answer, but was kinda hoping against hope that maybe the tech had really improved since the late 1990s/early 2001. Oh well, the more things change..
The tech might have improved, but it has used those improvements to get more computing power out of each Watt. And of course, games need more computing power now, too, for better graphics and physics...
My only suggestion is to ensure that your Notebook either has Windows XP or WIndows 7. Both require less power (computing and electricity) than Vista.

I personally prepare Windows 7, but I am the kind of guy that jumps on the new and shiny - and also work and develop for it since a while now...
Aside from that, you should ask yourself:
- How mobile do your respectice notebooks to be? Do you want to use them while aboard a plane or train? Or do you merely need to fit it into your suit or brief case and unpack it only at a hotel or office?
- How much gaming do you expect to do when travelling?
- Are both of you going to game at the same time?
- Do you expect to switch a lot between gaming and working on the notebook?
- Are you more interested in surfing or working on your travels?
I think:
- If you're mostly focused on getting online, a netbook will suffice. You won't store many personal or work-related files on that thing, so it would be easy to share the netbook with your wife without many conflicts.
- If you want to work, a notebook with a little larger display (and keyboard) will probably be preferable. Also, you will keep a lot of your files on it, so you want to use it most of the time.
- If both of you game a lot, both of you will want a high end machine. If only one of you does game a lot, a single gaming machine should be enough.
- If you don't really have the time to game while travelling, you probably don't need a gaming notebook for that.
- Working in a train or plane requires a small notebook, you just don't have that much space to "unfold" it or to transport it. A 15 inch display might already turn out to be too big, 13 inch and less are probably better.
- For gaming, a notebook in the 15 to 17 inch area is probably a good idea, and I don't think you will find smaller ones anyway.
- Gaming at home does not require a notebook. A desktop can be fine, giving you more performance for your $, allowing you to use a big (19, 22 or more inches) display.
Upgrading possibilities and all that are nice, but unless you want to do that yourself, I wouldn't really put this as important. It's always a hassle, even if it comes out cheaper.
It's possible that you two might be well served with two different notebooks - one gaming notebook and one netbook. As long as you don't get envious of each other.

("Why do I get the kiddie notebook again?")
Maybe a combination of desktop/notebook/netbook would also work great.
Of course, the easiest solution might be to get yourself two identical notebooks. This way, you need to learn only one machine and can help each other out with technical issues.

That might get expensive if you want full gaming capability, and it will not be very useable.
When it comes to technical equipment, think about what kind of "new tech" do you want?
- HDMI support? I use my notebook (macbook pro) as my DVD player most of the time, it works better than my (albeit cheap) dedicated DVD player. And of course, you can also bring Hulu or similar services easily to your big TV this way.
- Bluray? Some Sony Vaio notebooks come with that - we just got my father one to his 50th birthday. It looks pretty decent... And you don't need an additional device.
- Multitouch/Tablet PC functionality? A lot of new stuff happens in this area, it remains to be seen if it is just "cool" or actually something that will become more common.
- Docking Station? I personally don't really see the big benefit, to be honest, as long as you have a VGA/DVI/HDMI Out to connect a monitor or beamer, and enough USB ports for USB sticks, mouse and an external keyboard (if you want one).
- Bluetooth. Wireles mice, mobile phone data exchange and more?
- Flashdrives or "regular" hard disk? Flashdrives are faster and, without movceable parts, don't have trouble working when it gets a little rougher, but they are a lot more expensive and offer less space.
When it comes to software, look out for special offers. For example, I think there are some Office Student and Home licenses for families for example, and simillar offers for Windows.