Okay, I'm sorry but I think you are over-reacting quite a bit and are "stuck". First, I bet your 3 year old LOVED playing with those pennies and the only thing that concerned me was that they are such a choking hazard! (You didn't even mention that in your list of complaints.) Second, it's truly not g'parents JOB to provide entertainment for your children. It's not. If they do, that's wonderful and great, but mom, it's YOUR job!! Don't use the excuse that you, the fulltime mom of these children, forgot to pack toys for them to play with. You want to criticize somebody---who forgets to pack toys for their kids to play with? Seriously. You are driving for only 45 minutes, so how on earth can you NOT have room in your car? I don't care how small your car is since they all have trunks, cargo holds, etc. You could easily pack a box of toys or two or even three boxes. You are not being reasonable about this situation. When my first was small, I packed a box of toys that I bought just to leave at my parents' home, and we left them there so they could have new and exciting toys to play with while at g'parents home. Never in my wildest dreams did I expect my parents or my husband's parents to buy toys to entertain my children. At my in-laws home, I always packed toys and snacks for my kids to eat, and you should do the same and quit whining about them. Your kids will enjoy (or not) their relationship with the g'parents whether they buy them stuff or not. If you are seriously worried about gifts, pick the phone up a month before each b-day and Christmas and ask them if they'd like a few gift suggestions to choose from for your kids. (IF they do email, you could email them the suggestions and even some links to Amazon or where ever so they can see the prices and even buy online if they choose.) Give them a suggestion for an inexpensive and a moderately priced gift for each of your girls. If they come through, great, but if not, don't sweat it---it's such a small thing in life to complain about.
As far as the alcoholic drink in hand while holding a baby---was it the first? If so, I personally wouldn't sweat that, either. Does she get drunk? That would be out-of-line, of course. And you are within your rights to ask your husband to have a quiet conversation with his parents (in private) that you both would prefer they not drink while holding your children, and if they forget and do so anyway, just have hubby gently take the child. If they say something, he can quietly whisper a reminder of your request. It truly would be best if he handled this, and if you back off all the other stuff, he probably won't mind. But if they don't over-indulge, I don't see the big deal here, either. It's not like they're driving your children or babysitting them while drinking.
As for the inappropriate gifts----if it's too old, you can say something like "Oh, she'll enjoy this so much when she's older. Thank you so much." Blow off the rest, mom. You are too invested in criticizing your husband's parents. Be thankful they are alive and healthy and can have a relationship with your children. Forget the rest. Find as many GOOD things as you can about them----force yourself to find a pre-determined number of positive things about them at each visit, and chat about those good things in the car on the way home with your husband and your kids. Do not allow yourself to give voice to those negative things you saw. To anyone. You will gradually stop thinking about them and finding them as often, and hopefully will start noticing more and more good things, and begin enjoying your visits with them. And as for you two not meshing well and her not returning your calls----can you blame her? Sounds like you are blaming her for not being this perfect grandma you have pictured in your head.