Seths,
I love tractors, everyone should have one...or two...or three.... /forums/images/graemlins/cool.gif
That being said, it looks like I'd have to agree with the ZTR recommendation.
Case in point: At my last place, the grass grew very fast and I worked long days at my real job. This meant that when I got home, I was either tired or it was late. It rains on many weekends, and on days I did go out to mow, about 1.5 acres were shaded from about 1pm on. This makes grass slightly damp.
I had a 20hp 48" riding mower. Wound out, it would still bog down or leave so much cut grass it looked like I was making hay /forums/images/graemlins/confused.gif The mulching kit helped the cutting, but had to be very dry. I bought a lawn rake, but had to keep emptying the bag while raking- and this was a 42" rake...
Long story shortened... I hired a company to cut my grass (I was ill for a long period) and they showed up with 2 ZTRs and a weedeater. They cut ALL 2 acres and trimmed the house and landscaping (3 people total) in about 20 mins!
They must've been mowing at 10-12mph (guessing, but it was about as fast as my little garden tractor would drive wide open). Didn't matter if the grass was damp or even wet one day.
Granted, there were three of them and two mowers, but that would still make it about 1.5hrs for you, figure 2hrs because you'll mow around stuff.
ZTRs turn on a dime (hence the name /forums/images/graemlins/grin.gif). Makes cutting around trees, landscape, houses, etc easy.
They mow fast, clean, and are easy to transport with a smaller trailer.
I bought the tractor for here because we are doing landscaping and other farming related activities, otherwise I'd be using a ZTR.
Don't go cheap on a ZTR, there are major differences between the cheap ones and the commercial versions. I'd say between $5k and $7k depending upon what you want.
Good luck and let us know what you decide.
-JC