Judy, I do know how you feel. When Abigail was 4-12, she spent every weekend at my house. I loved having her, but I work and it really was a chore to have her here and get everything done I needed to do. It was a relief when she started athletics that required her to play/practice almost every Saturday (so she didn't stay over - maybe Saturday night only). Then, she developed so many friends about age 11-12, and they all visit each other over the weekend. So now, she hardly ever stays over and I really miss her sometimes. But I see her a lot, go to her volleyball games, and stay as involved as my time will allow.
However, I just don't think I'll be able to take Emma every weekend like I did Abigail - although Emma may not want to stay with us - who knows. I have so much more to do with Gary now, and he needs a lot of my attention. After his best friend died, he doesn't go out much, and his health is much more tenuous now anyway, if he was running around, I'd just be a nervous wreck! Yet, I don't want Emma to not be able to stay with us some of the time - however, I just don't think I can keep her every weekend. Now, that may be a moot point if the kids have to move to Houston - which is looking more imminent. Of course, then I will be so sad that they are 3 hours away, and I can't run over to see them any time I want. Although in some ways, that will be better. But I will still be really sad!
Anyway, I do understand your feeling like you are at their beck and call all the time and I know that doesn't feel very good. I need my space and alone time and the older I get the crankier I get when I don't get it. I have fallen into the trap of picking up my mom from church and taking her home every Sunday at noon (she rides to church with a friend, but can't ride home with her and the church is near my house). She called tonight, and I just thought, "I don't know what I'm doing tomorrow and I need a break from picking you up!" So, I told her I didn't know what we'd be doing and to call me tomorrow. I'll probably pick her up, but grrrrrrr........
Maybe that is even more reason to get away to FL for part of the winter! Maybe I'll join you! LOL!!!