Well all you need to do is turn right when leaving the NI-BMW show and you're striaght on the Antrim Coastal route that will take straight to the Giants Causeway if you so wish!

If you're up that way then its definatley worth going over Torr Head.

As Listermint says, Donegal should get a hit, great drives to be had. The Atlantic Drive around Fanad head and Downings etc is a must! There is a couple of decent hotels in Downings.