I recently flew via AA, and returned via UA. I consider myself normal-sized. AA had a gorgeous, new aircraft with about 30% less room. The guy next to me might as well have sat in my lap, the seats were so narrow. Physically, that seems dangerous to me.
On the way home, I flew on an older, thankfully "bigger" UA aircraft. DEAD LAST row, because you can no longer choose a seat unless you pay extra $$. Thank golly the middle seat was empty. I could exhale. Have you flown lately? What was it like?