If I use scalapack and pblas, and the code is run in serial (1x1 blacs process grid), how well does scalapack and pblas revert to the performance of lapack/blas?
I am particularly interested in the pzhegvx and pzheevx routines with $n \approx 1000$ and the pzgemm and pzherk routines with $m,n \approx 1000$ and $k \approx 100$. These are the lower bounds in the space of reasonable inputs. Otherwise, as Jeff points out, scalapack wouldn't make a whole lot of sense.