While I am not super tall, I am heavy. The one time I got to fly international first class was the first and only time I could sleep on a plane. I got a nice large bourbon, fluffy comforter, pillow, and burrito-ed myself in that pod. It was utterly glorious. I was glad that I wasn't paying for it... Was something around 4k for a 5-6 hour flight.
If the flight is international and sufficiently long, getting better seats is worth it. Better food. Free booze. Lounge access (it depends...). More space. If the price is right, get first.