Wedding Etiquette

So we're going to a wedding in Jan (which is summer for all those not downunder!) and the wedding ceremony starts at 5:30pm. The big dilema has settled in about what to wear. The definition of lounge suit seems pretty varied, and couple that with potential for stinking hot evening here in Oz is very likely so I'm backing the well trusted beige linen suit, alas not seen eye to eye with rochelle who thinks it should be dark.... bugger it why don't i just go in board shorts and tux jacket. We did this at the buck / stag do and it went down very well in Airlie Beach... not sure if the bride would see the same humour value in the hunter valley ;-)