We see MIL every weekend, but she is family, we have always treated her as FAMILY... i.e. Life goes on, if I need to pop out whilst she is there, I do, if she needs to whilst we are there, she does.
At ours, I do our online banking, hang the washing out, do whatever needs doing - she'll make me a cuppa, spend time with the kids, watch a film, have a snooze on the sofa, whatever.
At hers, we cook a roast dinner together, she'll ask for help with the computer/phone/kindle/hudl or flit round doing the jobs she needs to do, one of us will make her a cuppa.
The kids are teens now - sometimes they will be there, sometimes not, sometimes one of us will be there, sometimes both. We see each other every weekend, but it is not a chore - never got this "entertaining family" business - they are family, get mucked in, live "around" each other... make it so from the start.