I'm a big young fatguy. I'm not so fat it affects my mobility, but I couldn't fit through the rock in the Fairy Glen to reach the top of the rock, which was disappointing. A couple of years ago I was able to get "Economy Comfort" on KLM for an extra 5 or 8 inches of legroom, and it was totally worth it. The normal seats were okay, but if you can spare the ~$175 each way, it's more relaxing.
"Kitto daijoubu da yo." - Sakura Kinomoto