Background: My parents live overseas. The flights for all of us to get there are extremely expensive, so not really worth going for less than 10 - 14 days. We haven't been to visit them for nearly three years, although they have been over here quite a few times and I met them with the kids recently at their holiday house, which is also in another country but much closer and cheaper.
I've been looking at flights to go and see them at Easter, but am having serious doubts due to the somewhat strained relationship between my dad and 6yo ds. It basically boils down to my dad having much higher (and in my opinion fairly unrealistic) expectations of ds's behaviour than me and dh, which has got worse as ds has got older and therefore more "responsible" for his actions, but they have always wound each other up terribly.
My dad finds all children and normal childish behaviour incredibly irritating, although he seemed to manage to put up with me and my brother ok (he did work long hours though and was often away for long periods of time). He seems incapable of defusing any kind of normal child-related situation (say ds wants a particular tshirt that is in the wash - instead of a quick distraction he'll pounce on it and really wind ds up about it and then get cross because ds is shouting) and uses things like sarcasm in such a way that ds completely misunderstands him and gets upset.
Ds is definitely no angel but I have tried very hard to see this from all points of view and I really don't think I have my head in the sand about his general behaviour - I wouldn't describe him as "spirited"! 
. He can sit and and eat nicely in restaurants, sit quietly through things like church services, is often kind to his little sister and helpful to me. He can be very loud and bouncy (ok this is quite often!), sometimes whingy and occasionally shouts and is rude, when he gets told off and usually sanctioned in some way after a warning, but surely every 6yo is like this sometimes?
I found the last two visits quite stressful, and end up trying incredibly hard to control ds's behaviour to an extent to which I wouldn't normally go, then feel huge implied criticism of my lovely ds and my own parenting every time my dad looks irritated. I spoke to my mum today and she said that dad had tried very hard not to wind ds up this time - I couldn't tell 
. I don't want to spend £2,000 on two weeks of annoying my dad (who I love, and is actually a very nice bloke once you remove any children from the equation!), ds being upset and me and dh (and my mum) all being constantly tense. Should I just accept that we will see my parents even less often and not subject us all to this until ds is older? I can't see any way round it 