Though I'm a US refugee ... it looks like US (or at least a *A carrier) is the way for you to go. I only say US instead of UA or (soon) CO because of the free unlimited upgrades and the lack of filtering on awards on US.

For your international travel, you can connect pretty conveniently in Charlotte for LHR, CDG, FRA and for other European cities you can take UA via IAD or CO via EWR once they join (I'd avoid US via PHL). As a *A Gold (which you'll hit pretty quickly with your travel schedule) you'll have full lounge access when going to Europe.

US flies PHX to both Anchorage and Calgary ... however there is no non-stop from PBI-PHX ... so if you're unwilling to go to FLL or MIA for a one stop to ANC or Calgary you'd have to double connect.

You can fly PBI-CLT and PBI-PHL non stop on US.

Also, PBI-ORD you can do non-stop on UA and PBI-IAH you can do non-stop on CO once they join.

You can also fly non stop from PBI - Toronto on Air Canada.

*A seems the way to go.