On the 777 you will find a 2-3-2 config. The first two rows on the 773 and first 3 rows on a 772 are in a "mini" cabin and much more pleasant compared to the much larger cabin behind. Avoid seat F on any row. It's a seat in the middle of a row of 3. If you take isle E or G on a not fully booked flight chances are quite high you'll have an empty seat next to you.

On the 330 you will find a much nicer 2-2-2 config. The plane is quieter too. 2A and B are the best. Again two cabins, the rear being slightly smaller, but I like the forward more in rows 1-4.

You are right about the seats. Seats are the same accross the fleet, except perhaps on some newer 777 where they are a bit better in details. Ive read reports they are less good on 747 but that I can't confirm. The seats are arguably below average compared to what you find in the industry nowadays. However, I find them comfy enough and I sleep reasonably well in them. The biggest downside for me is the fact that you cant't realy lounge "wide" when the seat next to you is occupied.

For more advise:
http://www.seatguru.com