I was in Target yesterday and they had some really cute liquor dispensers. Globes, gas pumps etc. That might be a good FIL gift.
You can go to Target.com and search "liquor" to see them (I tried to link it for you but I'm not allowed yet )
As for the MIL, what about some wine glasses and wine? Maybe even arrange in a nice basket or hatbox?
Or even one of the Target dispensers and then a gift certificate to a good wine/liquor store. Sure, it sort of implies you think they're a little alcoholic, but oh well... at least you know they'll use it. You could even make that a couple gift - whenever I am buying for a couple and one of them is the hard-to-buy-for type, I just buy something for the other person and put both their names on it. Maybe then she'll get the message that you had no idea what to buy for her and start making more of an effort to help you get to know her better.
I've been married into one of those strange families for a while, so I gave up trying to please them all a long time ago. As long as you can keep at least one of your in-laws in your good graces you're doing better than some people