Welcome to the DIS C.Hjorth!!!
The only sit down restaurant that you have a chance to see Illuminations from is the Rose & Crown in the UK. They have a patio where you can request to be seated. They will not guarantee that you will be seated there, but you can request it when you check in, and offer to wait for a table, if you are willing. We have been able to sit on the patio 2 of 5 times we have eaten at the Rose & Crown and we had requested it each time. There is a place where you can stand and watch if you have been seated inside. It is a nice restaurant either way.
Another option for a CS spot is the Cantina de San Angel in Mexico. They have outdoor seating right on the lagoon. These spots, however, fill up early and you may need to be there 90 minutes, or more, depending on when you go.
Hope this helps.