I've been on the A330s in biz, and they are very comfortable. You'll have a nice ride.

My partner and I are atypical in liking the 767s at least as much. We are both 6'+, and broad-shouldered, yet have no problem with the width of the 767 biz seats. They are comfortable to nap in, and we both seem to sleep better in the recliner position most of the time, compared to the 170deg lie-flat.

I've written some detailed reviews and comparisons of the seats in the trip reports, either on Flyertalk or Airliners.net. Just do a search on my username (same for both sites).

There is more than enough room, with plenty to spare, for bodies our size in either seat. The 767 seats are softer, but not lacking in back-support. The A330 seats, with the canopy, provide more personal privacy and more space between your head and the head next to you. This can be particularly beneficial if travelling alone. The 767 seats have never felt cramped, but there is definitely less space between seats than on the A330. We enjoy each and don't book specifically toward/away from either aircraft.

When I first sit in the A330 seat, it feels uncomfortably-firm, but that improves very quickly, perhaps as the foam in the seat cusion warms up. It also feels at first like I'm going to tip forward out of the seat. I find that by using the seat controls to nudge the thigh-support forward while the plane is still on the ground, the seat suddenly becomes way more comfortable for sitting upright. I usually keep the thigh support in the slightly-forward position on the ground and through takeoff, with the rest of the seat in its original position, and that seems to do the trick.

Enjoy!