I've flown on the 777 to / from Glasgow and on the A380 on a connecting 12 hr flight.

I agree with Will08 that the 777 seat feels more like premium economy. The seat is angled lie flat. I had a window seat and the partition was pressing against my shoulder for the whole flight. I definitely preferred the A380 flight. The meals and the service by the crew were perfectly fine.

It's a 7 hour flight though. I don't know how much benefit you'd make of the A380 facilities. And even with lounge access, I didn't find Dubai Airport that interesting. I had a 9 hour layover and I was happy to see the boarding call for my onward flight