  In this paper, we show that any subgroup of a semidirect product of Z^n with
Z has bounded packing as long as the action of Z on Z^n is by diagonalizable
automorphisms all of whose eigenvalues are real. We use this result to show
that any subgroup in a polycyclic group of length 3 or less has bounded
packing. We also introduce the notion of coset growth and obtain a bound for
the coset growth of subgroup H=<t> in the semidirect product of Z^2 with Z.
