Value is entirely subjective. Point for point, if you don't care where you sit, BOS-CPH is probably poor value because it usually benefits from good tail winds and decent routing. We left 10 minutes early and arrived 45 minutes early (and that feels typical of my last four flights on that route). For me, the value comes from the more spacious seat and not having anyone sit next to me. If I could get the exit row seat in Go and a guaranteed free seat next to me, I would have no problem flying Go on that route. But I was originally booked in Plus and I know lots of people upgrade from Go to Plus so no chance of an empty free seat next to me.

I've been in the D1 Lounge in Boston on a DL ticket. Honestly, you're only missing out if the table-side service is what you really want. Otherwise, perfectly good and delicious options in the main lounge, especially as the SK flight leaves early evening so you get to the lounge when it is not busy and everything is fresh. Of my date of travel, there were BBQ spare ribs, BBQ chicken, four salads, two soups, great side dishes, Italian pastries from a North End bakery, slides and wraps, and a well-stocked bar. I ate and drank like a king - which was fortunate because most of the food on the SK flight was inedible. Besides the prestige factor, I would actually prefer main lounge to the D1 Lounge in Boston.

Now the JFK D1 Lounge is a different matter entirely