Ah ha, one of my favorite topics, comparing vehicles!!
Phil beat me to the punch and captured the comparison perfectly, I would just add that the Venza beats the Rogue in most categories but not all, and it depends on what your priorities are. My priority when purchasing was:
Fun to drive AND excellent utility AND medium size (not too big, not too small) AND excellent fuel economy AND low price. The answer for me was the Rogue and no others came close. The Venza wasn't available in 08 but even if it was I wouldn't have purchased it because it gets sub-par fuel economy because of it's size, it's a little too big for me, it is a little low and car-like and wouldn't be as fun to zip around in, maneouver in parking lots etc.. The price is higher than the Rogue, so going with my priorities the Rogue beats the Venza.
If your priorities are a BIG engine, slightly larger crossover, lots of gadgets, and quality and you aren't too worried about price or fuel efficiency then the Venza beats the Rogue. The Venza does come with a large 2.7L 4-cylinder which makes roughly the same numbers as the Rogue (just 10 more horsepower) so you might not gain much there, but the 3.5 L V6 would be vastly superior to the Rogue in terms of power, smoothness and noise. The Rogue engine is quite noisy and the Venza 3.5 would definately be quiet and smooth in comparison, but like Phil said, you can't really compare these two directly as they're in different classes and the Venza is quite a bit more expensive.
As a side note, the Rogue is my "big" vehicle, I have one 2-yr old who I've hauled around in the Rogue since she was born and this vehicle has been great, we're planning on having another child soon and the Rogue will handle 2 car seats with plenty of room, as I'm sure the Venza would too.
In terms of quality, you can research and compare the Venza to Rogue at TrueDelta.com - I think both have very good reliability. One thing I will note is that my Rogue has it's share of minor cabin squeeks and rattles, nothing major and I'm not sure if I'm typical, also don't know if the Venza is the same but I'd say the Rogue is about average in terms of "quiet cabin".
I'd recommend test driving all 3 vehicles, do a side-by-side comparison of the specs and prices and I think your favorite will jump right out at you. Good luck!
BTW, you might want to have a look at this thread too:
zer...-copy