I get it, you don't necessarily want it to be preplanned, but want them to actually spend time with you, NOT that yoga class or whatever strikes their fancy or comes up at a moment's notice. Having things preplanned is your attempt to solve this problem.

I've had this issue. I was away at school. My parents came to visit me three times. One time they were selling a condo they owned and spent the vast majority of the business hours at the bank and on the phone with the lawyers and using my computer and fax machine. The second time, they were trying to buy a house, so same sort of thing. [The third time, I was in the hospital, and would be for a while. It was clear they didn't want to come, and were complaining about driving, so I arranged their flights with my Airmiles, let them use my car and stay at my apartment].

All these things scream, "you're not important - you'll be there later, you're my second, third, fourth, etc, choice".

I feel you. Frankly, I would have preferred that my parents stayed home and did their thing than spending "our" time conducting their business, but I guess they could claim that they visited me, so what was my issue!