You make a very good point. These hotel programs should have a permanent field for required ADA/accessible rooms. I have been given more of these rooms than I care to have ever had (and didn't want nor request), and from time to time, that is all that is available to book (or is substantially less rate than others, not even requesting it). If this is the option provided, I always put a note in the comments field that I DO NOT NEED the accessible room. I would certainly hope that with advance reservation, most hotels would be able to accomodate you most of the time, and advise you IN ADVANCE if they can't.