I used to feel the same way. It largely depends on who you are pairing with. Nearly every experience for me was unique. The part I keep chasing after is your first point. I usually work that way when solo. But with a good pair, it is the same effect without all the planning. If the other developer is just as good as you are, you will inspire each other. One of you will try something that doesn't pan out, but with give the first a new idea that does. It is an amazing experience when it happens, though a bit rare.
The exhaustion you get used to. I feel more tired after 8 hours of pairing than 18 of solo.
It hardly seems worth the trade-off. The more exhausted I am at the end of the day, the less inspired I am the next day. And trading two (experienced) developers' time for a rare chance at an epiphany doesn't seem worth it, either.