Boy, we have all the extremes covered on these boards! 20:41, I respect your nuts but damn! You're a stickler. I admire it, though. I really try to compromise a bit, but every year I feel like the inch I give is turned into the proverbial mile, and that despite my efforts to compromise, my in-laws still see me as a cranky fun-squasher and despite my effort to rein things in, I still end up feeling overwhelmed.
My husband and I had the same talk, and had the same "same page" feeling, but when his parents come loaded with enormous, computery / yappy / electronic gifts, he doesn't speak up on the spot. He waits until after time has passed and then it's obvious that the big bad wife put him up to it.
Despite how this thread sounds, I do like my in-laws. I just wish we could get the gift / spoiling stuff settled. Like OP, we see them between every month and every other month. I really don't want to be TOO heavy about things that might not matter that much. So I do choose battles. I might not have told my inlaws to their face that we were off to goodwill with their unwanted offerings, as the fall out and hurt feelings from that would be unworth it. But...I do put my footdown on stuff like the cupcake issue, juice, etc. MIL is the type who is all "how about some juice instead" when DS asks for water. So we had to put that in check. And she was also giving him marshmallow cream once when he was like 11 months old, which yeah, I nearly lost my mind over. I don't wait for DH to step in on those, I just nip 'em. But it's hard to find the right balance between harsh and doormat!