I am an extremely technical user (15 yrs Linux admin) and I have both a netbook and an iPad. As soon as I got the iPad I stopped using the netbook. The experience on the iPad is far FAR superior as a consumption device than a netbook. If you are trying to use the tablet for the same things as your laptop, you're using it wrong. It sounds like you don't have a tablet, so you really don't have the credibility to weigh in on it.
Also, I would suspect that your wife would highly prefer a tablet if given the chance to try it out. The netbook experience is truly horrible -- she just might not know that something better is out there.
Consider how she likes playing all the crappy Flash-enabled games she gets her hands on from Facebook, or how she depends on Microsoft Office for work related stuff, I beg to differ.
The netbook experience is indeed horrible, however you can attach a real mouse, a real keyboard and a real monitor to it, or a combination of those, any time you want.
My colleague has an iPad. He doesn't use it. It just sits there on his desk. I played with it and it has potential because of the touch-screen. However, as long as it is a dumbed-down device, it's not useful enough to bother.
I have an upper end desktop, a cheap netbook and android phone, a PS3, and a kindle. My family has a shared Ipad and my wife as a reasonably powerful laptop I can borrow sometimes. I use all the others to supplement the desktop, but even together they couldn't replace it.
My desktop is the focus of my digital world. I use it for my programming, for writing papers at school as well as for gaming and media consumption when I am at the house. It does things like run multiple VMs and compile code in a reasonable time that none of the others manage. With its dual monitors and easy ability to handle numerous programs at once, I find it tops the others even for tasks like e-mail and web browsing that the Ipad does handle well. All of those others combined cannot replace what I do with my desktop. Even with her fairly high-end laptop and access to the other tools, my wife often borrows my desktop when she is doing serious writing for her PHD.
The others supplement my desktop for niche tasks. I take my netbook to class to take notes and it is good enough for light programming/paper writing and writing when I am on a trip (and I consider it a small PC, not a PC competitor. Also, I find the netbook quite nice for its good-enough travel computer and in-class-note-taking.). My smartphone is a game changer since it is always with me. The kindle is by far the best device for reading and I now prefer it over physical.
The Ipad though? It mostly has games for the kids since it is simple enough for even my 3 year old to use. I sometimes take it with me to places like the airport or DMV where breaking out my netbook would be a touch awkward and it has a pretty good Go program on it.
In short, I think for people doing serious content creation or serious gaming the PC will live on for the forseeable future.
Also, I would suspect that your wife would highly prefer a tablet if given the chance to try it out. The netbook experience is truly horrible -- she just might not know that something better is out there.