I actually thought the same as Brandon, wrote this, then decided that it was not actually so after all.
"Shall" is not really the first choice nowadays, but I thought, talking with friends, it seems fine for such an informal question.
Let's ... seems to suggest that we should and seems therefore more leading an answer of "yes".
Shall we, in this sort of use seems quite natural and neutral, as if the place is the suggestion.
How about, we get together ....also an option, butr again leading.