Depends on when the conference is scheduled, but Mexico has some world renewed venues at the seaside - say Cancun- that nobody minds visiting when it’s winter at home. :-)
It's much better value for money than anywhere in the US.
Those guys were pretty smart
I got my first taste of this with this was a summer school at Les Houches in the French Alps [0], and after graduating I did postdoc positions on three different continents -- all the time appreciating that unlike corporate expats, I got to choose the exact place to go next. Would highly recommend this way of traveling over backpacking.
[0] https://www.houches-school-physics.com/ecole-de-physique-des...