Sounds awful to say I know but I find them incredibly draining to be around which is only getting worse as they get older.
Both are retired, in reasonably good health, no money worries. Father just sits on the computer all day editing obscure Wikipedia articles no ones reads (no, really). He has no friends, no hobbies, completely dependent on mother for the domestic stuff (washing, cooking etc.) - idea was he'd pick this up after retirement though nothing's come of that. He's borderline OCD and it's exhausting having to tiptoe around this - 'mess' in the kitchen whilst cooking, things placed on the 'wrong' shelf etc. Gets in a huff if you challenge him.
Mother spends her days drinking wine and getting in arguments with dad, neighbours, shop assistants etc. Again no real friends. Completely estranged from remaining family.
'Family together time' means sitting in front of a TV watching rubbish at deafening volume. Every time I visit (I live a long way away thankfully) I'm constantly on edge, tiptoeing around their moods and outbursts and feel like I've timewarped right back to childhood.
I've already reduced visits to the bare minimum, though there are several family events coming up I will have to attend and I'm seriously considering getting a hotel rather than stay at their house, though I know this will cause another argument as they pull their wounded puppy routine.
I have friends so say I should treasure the time I have left with them, though honestly I just find it a painful, stressful trial.