Sometimes you can't see the wood for the trees. Try 'Your child your way' by Tanya Byron for ideas on keeping a diary on triggers for poor behaviour, and ideas for how to manage it - although she stresses that no one method for discipline is right/wrong - it has to be something that works for your children.
Ours don't behave like that, although my 6yo does answer back at times, and I consistently respond with a reminder not to answer back/cheek me. I refuse to do anything for them unless they begin with 'Please may I...?' or 'Please will you...?' (bit old fashioned, but I just hate it when kids demand stuff).
I try not to sweat the small stuff, but if they have massive tempers or hurt their siblings, they go into the hallway for 5 minutes to cool down. If they mess around at bedtime, they lose the right to watch telly the next day. (FWIW they don't have TV/DVD in their rooms and no hand held PCs/gaming devices - all screen stuff is on the family TV or laptop so it can be timed & monitored, call me a control freak if you like 
).
We talk a lot about how lucky they are - I bang on a bit about the fact that they get to do stuff and have regular meals etc., just so they don't take all that for granted. If they ask for comics in the supermarket I make a point of saying No 80% of the time - they've got to learn that they can't have what they want all the time.
If they throw tantrums, I either totally blank them, or show them how silly they look by pretending to do one too (only in private though!)
I sometimes lose my rag and bellow at them, but try not to, and feel guilty when I do (like all parents). I know there are certain flashpoints, e.g. before dinner, when they are hungry; if they're particularly tired in the evening. However, they are generally good kids, and I'm sure your DS is too - sometimes you lose sight of all the lovely stuff they do, so try not to lose sight of his good points too.
And finally, it is hard to think of stuff to do with them over the hols, so you could try a 'boredom' jar: put pieces of paper into a jar with 30% chores, 40% general activities and 30% pleasurable stuff. If he say he is bored, he can pull out a piece of paper. He has to do whatever is on it - it might be eat an ice-cream or bake a cake; it could simply be read a book, colour a picture, or it might be tidy his bedroom, learn his spellings etc. The threat of doing a chore might make him go off and find something to entertain himself :)
HTH.