  We construct a family of equations of state within a quasiparticle model by
relating pressure, energy density, baryon density and susceptibilities adjusted
to first-principles lattice QCD calculations. The relation between pressure and
energy density from lattice QCD is surprisingly insensitive to details of the
simulations. Effects from different lattice actions, quark masses and lattice
spacings used in the simulations show up mostly in the quark-hadron phase
transition region which we bridge over by a set of interpolations to a hadron
resonance gas equation of state. Within our optimized quasiparticle model we
then examine the equation of state along isentropic expansion trajectories at
small net baryon densities, as relevant for experiments and hydrodynamic
simulations at RHIC and LHC energies. We illustrate its impact on azimuthal
flow anisotropies and transverse momentum spectra of various hadron species.
