Well, SIAWOL, you've heard a lot of different opinions from a lot of very knowledgeable people. What are you going to do?
I hope you're starting to get the opinion that, as CGeib said, the ski length is far less important than the instructor who is teaching the class. And, despite what my esteemed friend and colleague Wigs suggests, the individual instructor is far, FAR more important than whether he/she works in a so-called "direct to parallel" approach.
Skiing is about movements and tactics, not positions. "Parallel" and "wedge" describe positions, and you can make both sound and unsound movements equally well from either one. That a ski school advertises "DTP" is absolutely no guarantee that the school, much less your individual instructor, will teach anything resembling good skiing movements. And no competent ski school that I know of has truly advocated a "wedge-based" progression in over 25 years--despite what many "DTP" desciples would have you believe. Good ski schools, and good instructors, teach movements.
On appropriate skis--which (to address your question) can come in a variety of lengths--an effective instructor can easily get most beginners on the road to great skiing very quickly. In the process, the student will very likely experience parallel and wedge, braking movements and gliding movements, and the whole spectrum of tactical situations where one or the other might be preferred. (It's relevent to consider that an expert skier, in the course of a day, will ALSO employ parallel and wedge arrangements, and braking and gliding movements. It is as big a mistake to suggest that "parallel equals expert" as it is to assume that "wedge equals beginner." It's a cheap marketing trick--don't be fooled!)
And this is true whether the approach describes itself as "DTP" or not. I can assure you that Wigs' excellent "Beginner Magic" program at Aspen teaches wedges when needed. It is certainly not "wedge-based"--again, no good program is these days--but I promise that they don't obsess over "parallel" either. They obsess over good movements! Their students may or may not ski with a wedge, and I suspect Wigs would agree that the instructors generally don't make a big deal about it either way--as long as the fundamental movements are right.
Anyway, this discussion is somewhat off the topic of your original question, and for that I apologize. The benefits of wedge over parallel and vice-versa have beeh discussed at length here at EpicSki, many times in the past--search the archives if you're interested. Your question is about ski length, and I just want to reiterate that a good instructor can teach good movements on virtually any equipment. Surely, a modern pair of skis meant for learning can make the process easier, quicker, and more fun. But it's not absolutely necessary, and such skis are no guarantee of a good lesson. An incompetent instructor will teach bad skiing on even the best of gear!
All this said, I'll cast my lot with those who recommend the very short learning-specific skis that have been out for the past few seasons, all else being equal. If--and only if--you are confident that you've found a top-notch instructor, then, if you have a choice, get your wife a pair of those wonderful little 120-140cm special learning skis (Elan, Head, and Rossignol, among others, have some great ones). But given the choice between a great instructor and older skis, or a less-than-great instructor and "perfect" skis, I'd recommend the former every single time!