I've never run an open mike bt have hosted singers nights at folkclubs as a stand in for the regular mc.

I wouldn't suggest save the best (which is only someones opinion) to last. I would suggest mixing it up. I knew the clubs regular performers and my policy was to try to mix it up as much as I could as I felt it made for a better night than having say 3 singers of the same type in a row. I also preferred to end with stuff everyone could join in with rather than giving a "star spot".

The club I was later involved with developed an interesting policy. It was to rotate hosts rather than have one person with thier preffered policy and inevitably preffered performers. I think it helped to some degree in keeping things a little varied - I do for example find it rather boring if I know for example that "Fred is going to round the night off for us with the same song yet again". Others may of course (perhaps even rightly) think Fred is the best performer and love hearing the song each week at the end.

Jon