Your building blocks are known as the *atoms* in the [Boolean algebra](http://en.wikipedia.org/wiki/Boolean_algebras) or [field of sets](http://en.wikipedia.org/wiki/Field_of_sets) generated by the $A_i$. Each building block will consist of points that have all the same pattern of answers for membership in the $A_i$. To see this, observe first that by maximality any building block will respect this equivalence and therefore be a union of such atoms. Conversely, if a set has points with two different patterns of answers, then it will contain points from two $A_i$ without being contained in their intersection. (Specifically, if $x,y\in B$ and $x\in A_i$ but $y\notin A_i$, then pick $j$ such that $y\in A_j$, and observe that $B$ meets both $A_i$ and $A_j$, buit is not contained in $A_i\cap A_j$.) So the building blocks are the atoms.

If your family is finite as you indicated, then the Boolean algebra generated by the $A_i$ consists precisely of the unions of blocks. This is the representation theorem showing that every finite Boolean algebra is isomorphic to a finite power set---the power set of the atoms. 

In the infinite case, should you entertain infinitely many $A_i$, then unfortunately, you don't get a partition, for there are atomless Boolean algebras. Nevertheless, these Boolean algebras are fascinating.