First, thanks very much for any insights. My brain is on overload trying to find the best combo of flights/prices/service.

What are your experiences flying BA Economy vs Premium Economy vs. Delta?

We're a family of four ( 2 elementary aged kids) flying Seattle to Inverness. We fly domestically a couple of times a year, but this is our first overseas trip together.

These are our options:
BA Economy via LHR for $630pp/$2,526 total including their ridiculous seat charges - 747
BA Premium Economy - same flight for $1,210pp/$4,842 total

Delta/KLM Economy via AMS for $766 pp/$3066 total on Airbus A330
Delta/KLM Comfort Plus - same flight for$1,099/$4398 total

I've only just started researching flights, but those economy seats seem like a great deal. I'm just not sure I want to spend double that for premium economy on BA when the reviews are really mixed. Pro on BA PE is the separate cabin, but it's roughly $500 more than Delta's Comfort Plus. Delta's regular economy is $500 more than BA, but we get to avoid LHR.

I appreciate your thoughts. I'm in analysis paralysis!