The flavors in this were so good together! It turned out soupier than I was expecting, but I think that was because I used pearl tapioca instead of instant - it's what I had - and I think I messed it up by soaking it in hot water instead of cold. Looking back on it, I could have just mixed the tapioca with the cold broth and tomatoes and let it soak in that overnight - since I mixed this up the day before and then cooked it in the morning. Either way, I'll try it again, whether with instant tapioca or the same kind - to see if there's a difference. It didn't really matter, because it tasted great. I just cooked up some fettuccine and served it with that and some sliced sourdough bread.
The original recipe called for bone-in chicken thighs, but I read it wrong and got the boneless thighs out of the freezer. I don't really like boned chicken in crockpot recipes because it ends up falling apart, and you always have to be on the lookout for bones. So, I stuck with the boneless. It was great, because it did fall apart, and there were pieces of chicken all through. I cooked it on high most of the time, and probably got closer to the 6-1/2 hours than the 4-1/2.
I used Great Northern beans, which I cooked in my crockpot, instead of the cannellini beans - because that's what I had. The original recipe called for 1/2 cup sliced black olives instead of the spinach, but at least one of the people who would be eating this doesn't like olives, so I left them out. And the spinach? The original recipe didn't call for it, but it just seemed like it should have spinach - so I added it. I didn't actually measure, but a 10-oz. package ought to be about right. You can add olives instead of the spinach or along with the spinach.
Update (1/29/16) - This recipe was Lori's September 2015 SRC pick over on lori's culinary creations. She added a handful of orzo to the crockpot along with the beans and spinach. I just finally got around to making this again, and followed her suggestion and added 1/2 cup orzo. I could have added a bit more, but it was really good. I am going to have to do that from now on.
Also, I used chicken breasts, because that's what I had. They aren't as good as the thighs, so I will definitely use thighs from now on. And, Great Northern beans are better than cannellini. I will use those from now on, no matter what the recipe says.