My biased vote goes to the ZTW. I own a loaded '02, and, if you're coming to the SVTOA Drag event on November 8, I will be there and you're more than welcome to take a good look at it.
It's a misnomer to consider the P5 a "wagon"... It is more closely aligned with the ZX5. The fact is, the ZX? and the P5 don't hold a candle to the cargo volume of the SE/ZTW wagon. Park all three side by side by side and open the tailgates, you'll clearly see what I mean
In the scheme of things, having another Focus is definitely a benefit to you. A Jetta wagon would be an OK alternate, but mainly due to its powerplant. I think, however, a PZEV equipped Focus would be up to par, with its potential.
The P5 is a smooth driving and relatively nice looking car that's as pleasing to drive as the Focus. One thing I was surprised with, when I tested my friend's, is that with the AC on, it didn't seem to struggle a lot. I thought that was kind of neat. He bought it used, with 20k miles on it. I'm unaware of its long-term reliability, but I'm sure there's a discussion forum out there where you can learn more.
The conundrum is this: if you choose a Focus, is it better to have the peppy PZEV and have only ABS, or is it more valuable to find an '02 that's equipped with ABS and Advancetrac stability control, for safety's sake? [The latter option happens to be egregiously absent from the current U.S. lineup