I'm going to Disney next month with my DS8 and DS5. I'm afraid that my DS8 will want to go on rides that I don't want to (I'm chicken) and that my DS5 can't or won't. I have the dilemma of wondering if I can send my DS8 (almost 9) on the ride while I take the chicken exit or wait just outside for him. He's very friendly and I'm hoping he'll talk to a family in line and they'll be friendly back so that he won't feel alone in line.
I think I'd be a little more hesitant to leave DS8 alone while he waited though. It doesn't seem as safe to me. But in either your situation or mine, it is not ideal. I think for us, we'll probably have to make compromises and all go on the ride or none of us. My DS5 is usually okay if scared because he'll cover his eyes and if loud, I cover his ears, so we might try some shows where he can at least sit in my lap.
I think it is an individual decision where you know your child best.
I've never gone alone, so we'll have to see. I have some reservations about my ability to handle the whole trip w/o DH, but I really, really want to go, and even though my kids don't know yet, I know they will be very excited.
Best of luck to you (and to me!).