I'm booking MSP-GRU and I've never flown UA internationally before.

Are the Economy seats just as tight as domestic flights? On domestic flights my knees always dig into the seat in front of me.

Are the Premium Economy worth the price? When I called UA they said they're "up to 5" more leg room". That doesn't sound confirmatory enough for $300-600/rt upgrade price. Any experience?

Are there any good seats in Economy with more leg room than the others?

Thanks in advance!