Rainbow has a small lot - try that first. If it is full, you can try finding a spot to parallel park on the street. If that doesn't work and you have to circle back around, you have a few options, depending on the time of day. You can try the public lot (free all the time) next to the cultural center or the pay lot just past Blue Martini (free during the day or pay after dark) or sometimes you can park in front of the Catholic Church if it is a non-church service time. Each of these locations will require a little bit of a walk (the farthest being the public lot) but, IMO, nothing in Grand Case is too far of a walk for even an average-physical-shape person.