I'm going with Miami on this one.
Miami is in the east....do I have to say more
Vancouver in winter is rock steady to most places east of the rockies.
Couple times per winter they seem to get an "arctic outflow"
that give Vancouver a few days where it struggles to reach 0C and they get some snow
and people go nuts
Like Tom77Falcons mentioned....you have keep your fingers crossed
when you book a winter vacation in Florida...even south Florida.
It's no Jamaica or Barbados, lol.
That's part of the reason why the islands (in true tropics) are still popular
for winter fun in the sun.
Florida in winter is better golfing, not really going to the beach.
Locals generally don't swim in the ocean in winter, heated pools maybe.