Girls “Wellness” Trip with kids

My M-I-L is organizing a trip next spring, girls only for a few days but with our kids. My twins would be 2 years old by then and my oldest almost 5. I was a bit bummed when she said kids should come. I won’t mind my oldest but the twins is literally not-wellness or vacation for me. It was said the women- (3 oldest ones) in the family will take turns babysitting and they don’t mind. The trip needs to be booked in a few months and I’d love to go just not sure if I should spend the money for a wellness trip without getting anything out of it. Any tips and advice?