That said, I'm an SP usually flying out of BDL and am at 100% (on upgrades to F) for my flights O/D BDL.

I'm not sure whether you can "officially" use the US club when flying UA, which flies out of the same concourse. Anyone else here know? Certainly, with the RCC or * upgrades, you can use the UA RCCs when you're flying UA.

When you're going to SJC, for instance, this means you'll have lounge access on your layover whether you fly US BDL-PHX-SJC, BDL-ORD-SJC or BDL-IAD-SJC.

Not sure where you're coming from, but also remember that US is well represented at HVN (they're the only carrier there), HPN and LGA, which can add some flexibility.

Finally, you seem to fly to Switzerland fairly often. If you don't already know this, US is in *A, which includes both LH and LX. If you buy the *A option on your US club membership, you'll be able to use LH's Senator Lounges in Europe when you're flying on either of them, even on intra-European flights.