Steve- I don't think anyone is disagreeing with you - just that it is complex.
I mostly play for the birthday/ fund raising sort of do so no point asking the dancers. I have an idea of the speed I'd like it played. Sometimes I will go down on the floor and demonstrate a move - usually to a bit of an easy tune with me singing. The band then pick up the tune speed and the key. They all look very pleased with themselves. When I get back to the band I find I'm having to play in something like b flat. Ouch.
Les - a whole A is OK ( good if you have people playing by ear) but a long time for the dancers to hang about. Do you all start together on the second A or do some drift in during the first A? It could sound raggity and give confusing signals to the dancers. I do admire the Scottish bands that start with a chord and Go.
FloraG