david, you can be sat round a trains station bored for hours, and not everywhere abroad is full of beer swilling chavs!
Where I holiday depends on what I feel like, be it a week relaxing by the pool in glorious sunshine or a city break, taking in the sights, a whole different culture and maybe praciticing my langage skills. I'd need to go abroad to do that. Although if I fancy camping I'll go to Wales, or if I fancy a quick weekend away I may got to Edinburgh or York.
You can see the UK whenever, so if I'm booking a main holiday it'll be abroad, that doesn't mean I won't be able to appreciate the UK as well.