No real advice but I understand where you're coming from, my XDH never goes anywhere with our DD or makes an effort to interact with her. Often on his weekends they sit at opposite ends of the house watching different DVDs. It's heart breaking at times but I've tried to explain to him the benefits of making an effort but he doesn't get it, or won't even try to understand.
Now she only goes to his house every third wkend as we moved away last year & they are both happy with that arraignment, I guess he gets let off the hook & she only has to be bored out of her mind once a month.

It is sad for your kids but they will eventually understand that you & your X are different people with different parenting techniques. I do have to say though that it's a tick in his square that he keeps the bath, dinner, bed routine - so many ex partners have completely different (or none) routines & that can be difficult for kids to understand.