You recaulked the shower!!! You already rock. Everything else from here on out is bonus.
And quite frankly... how much worse can it get? I mean, you could probably dance naked through the house and your MIL would just nod and say she's not surprised... so? Everything better than dancing naked just will make her (via your SIL) have to work harder to find fault. :) :) :) And you know if she has to work for it... you're winning.
Wanna know a secret? Do you know what annoys pitnicky people no end? Brunch. <evil chuckle> Brunch has this "put togetherness" that although they may gripe (and I've known sooooo many) there's this "pause" where they just blink blink and pretend not to be impressed. I'm dead serious. Brunch every day. ((Oh, I don't eat this, Oh I don't eat that... but when they go home... there's no way to spin it badly. Even the WORST that can be said is "No wonder she's so fat, she makes brunch every day!" -This is about me, since I'm twice the woman I used to be-. And MIL will get the news BRUNCH EVERY DAY??? It's a low blow. And it's one I revel in when I have to deal with nitpicky people... because It's all stepfordy...but Not. Eeeeeeevil leetle me. Hehehe. Because it's CHEATING easy, and it doesn't matter what any other meal of the day is... when brunch is on the table and all pretty in the morning. It's the first thing they see. Which is a hard image for people to lose. Fabulous dinners get forgotten as people sleep, but the image of the table with brunch every morning sticks with them all day and grinds the image in.
Bowl of fresh fruit on the table
Bowl of muffins or croissants on the table
Pitcher of milk
Pitcher of OJ
((it's worth the $20 to go buy 2 pitchers for the fridge just for their visit, and never serve out of the carton. Open a carton, dump it in a pitcher, replace in fridge.))
Cheater Brunch du Jour.
Cheater... because 90% can be cooked ahead of time and frozen (or plain old bought frozen). Defrost in the fridge overnight, and heat up in the oven on your way to pee. A little razzle dazzle right before you serve it (replate on a fancy dish instead of the tinfoil thing you froze and reheated it in and sprinkle of fresh parsely over an egg casserole, grate some fresh parm over tomatoes, dust some cinammon over challah french toast or normal french toast, dust some powdered sugar over cinnamon rolls, etc.), bacon and sausage without a house dripping in oil (cook ahead in large quantity and freeze) and it looks like WonderWoman spent all morning cooking... when really, you were mainlining caffeine and convincing yourself in the bathroom mirror not to commit various kinds of homicide) while the breakfast reheats in the oven. And leftovers, if they're nibblers, refreeze usually just as nice the 2nd time as the 1st!
HIDE the fruit and muffins/croissants if possible for Shazam! factor... OR leave out for 'snacking' and just direct folks to the table when they ask for snacks. Depends on their level of annoyance.
((And brunch means no lunch. Granted, if they N.EU they probably take tea... but we'll just ignore that and focus on not needing to do a whole meal 3x per day))
Something else you may forget living on Oahu, is how nice it is at NIGHT (esp if your inlaws are northern european, I'm making a large assumption, they may be Mediterranean or spanish and used to warm nights being the time when you'er out and about the most). A lot a lot a lot of the sites can be "seen" at night, and Waikiki is touristville... all brightly lit and full of music. AKA HUBBY CAN TAKE THEM!!! ((Ahem... because, after all, your young ones need you to put them to be. Cough. Ahem.))