Hope you find a good fit OP. I will share that when my oldest was younger we paid for full time care for awhile but had him go to grandparents on Fridays even so. Because the grandparents wanted that time and lowering hours in daycare was something we wanted to do, but couldn't figure out how to do any other way! The time with grandparents was so special and their relationship is still really special today, I think partly because of that time. So just sharing that it could be worth it to do even if you are just paying full time. We just decided that was the cost of things for us, but didn't mean we shouldn't take the opportunity to build that relationship if we can.
Totally hear the poster about grandparent burnout - know your parents/in laws. My in laws can handle this 100% and cherish the time. My parents are so wonderful, but can't handle regular full days like that. so it really depends and I'm assuming you know well whether this would work.
Do you have a neighborhood mom or parent listserv? I feel like you'd have better luck there.