Okay, I want to make chicken thighs as part of my work lunches for the week, and I want to make them very, very tender, so they can stand up well to being reheated.
These are skin-on, bone-in thighs, and I want them to be so tender that the bones come out easy, etc. What’s the best way to go about it? I have them marinating overnight and will be cooking them on Wednesday late at night.
Any advice is appreciated 
Crock pot cooking works great for this.
cook @ 350 for 1 1/2 hrs in liquid like broth or cream of chicken soup–cover for first 45 minutes–cook uncovered for another 45.
Pressure cookers usually tender chicken up pretty good.
I see you’re already marinating yours, but I used to bake them at 350° for an hour with 1/4" to 1/2" of orange juice in the bottom of the pan and baste them 2 or 3 times. They came out pretty tender.
Yep, crock pot, Dutch oven, a pot on the stovetop, pressure cooker–they’ll all work fine. Basically, you just want low and slow cooking until the meat falls off the bone. That’s all the trick there is.
Thighs, being exercised and muscular parts of the bird, have a lot of connective tissue, therefore a lot of collagen. What you want to do is break down the collagen into gelatin. Collagen turns into gelatin at around 140F - 190F, but it’s not an instantaneous process. You need to hold the temps and keep cooking until all the collagen becomes gelatin. Then, you will get the fall off the bone results you desire. How longs does it take? As long as it takes. Each piece of meat is a little different. For chicken thighs, I’d think about 1 1/2 to 2 hours at 325-350. My advice is to look up “braising” on Google. I would salt & pepper the thighs, brown them on a hot pan, throw them into a Dutch oven/casserole with liquid and aromatics of your choice, throw the lid on, and come back to check on it in an hour and a half.
You shouldn’t have any problem. Any low heat, long cooking time method will work. Chicken thighs are very forgiving.