Heading to Helsinki on St Andrews weekend and have decided to also throw in a trip over to Tallinn. Arrive late on the Friday so will have all day and night Saturday in Helsinki, then early ferry to Tallinn and most of the day/all night there, before getting the early ferry on Monday morning back to Helsinki (with another few hours until evening flight).
Any tips on things definitely worth seeing in both places would be great. Christmas markets are on the list. Gluhwein time!! :-D