I really love Alasdair--it sounds so noble and handsome.
Alastair and
Alistair are both nice, but can't compete with the original. Also, how are they pronouncing it? uh-LAS-ter? AL-as-dare? Something else?
Sorrel is interesting, but doesn't seem particularly feminine to me. The "sore" sound jumps out at me, and I can't really move passed it.
Ben and
Toby are both very nicknamey.
Benjamin nn
Ben is really nice, but so common.
Toby (and all of its potential fns) is a name I can only picture on a dog--even more so than
Molly,
Rufus, and
Rex.