  We consider several families of functions $f(\alpha)$ that appear in the
Bona-Masso slicing condition for the lapse function $\alpha$. Focusing on
spherically symmetric and time-independent slices we apply these conditions to
the Schwarzschild spacetime in order to construct analytical expressions for
the lapse $\alpha$ in terms of the areal radius $R$. We then transform to
isotropic coordinates and determine the dependence of $\alpha$ on the isotropic
radius $r$ in the vicinity of the black-hole puncture. We propose
generalizations of previously considered functions $f(\alpha)$ for which, to
leading order, the lapse is proportional to $r$ rather than a non-integer power
of $r$. We also perform dynamical simulations in spherical symmetry and
demonstrate advantages of the above choices in numerical simulations employing
spectral methods.
