Well I tried the suggested landing speed on a 777-200ER, it works well.
But on the 777-300ER, it drops like a rock!
Even with only 50% fuel in it and 1000 lbs on board..
The stall speed of a 777-300ER with 30 degrees flaps and landing gear down is around 175kts. Landing is around 180kts which works ok.
Yer prolly not using the right approach method. If you come in on ILS, you should be 190 KIAS between 20 - 8% of fuel on final approach (yes, even with the 777-300ER. Any 777 model). As your speed drops below 210 knots, let out your flaps... 1 -5 at 210, 10 - 15 at 200, 20-25 at 190 and full by 180. I am on the ILS beam 3000 ft ASL when I hit 190 KIAS (Use indicated airspeed. Alot easier). Drop gear between 1,500 and 2,000 feet. By this time you should be around 150 knots. If you're using an autothrottle approach, turn off throttle and hold down the F1 key to idle your engines. You should settle onto the runway, and flare while your doing this. If you flare too much, you'll tail scrape or drop like a stone, and if you flare too slow you might embed your nose wheel.
Also, try playing with weight settings.