Hubby was only able to use the RR discount on his one one-day ticket. That's all we needed, so he didn't try for more.
Oh, and wait...he didn't get that 20%. I've just remembered. It was Memorial Day weekend (Saturday), and the SW website that morning indicated a much lowered discount (probably b/c of the holiday).
So they used my brother's "passport" discount for the ticket, which was 20% I think.
We debated a long time about using the RR discount (before we knew it was going to be a bad one for our time-frame) or getting him a Fun Pass. My son and I have fun passes, b/c we visit my brother more often than my husband does. Hubby has used up most of his flex time (sick and holiday are combined for him) and couldn't figure out when he'd get down there before the Fun Pass ran out, so he just got the single day.
But for my son and I it has been worth it, b/c it was one day's cost, and it got us in twice in December (they started the promo last fall, when it was one day cost and you got the rest of '07 and all but 4 days of '08) and once in May. Well worth it.
But if you only NEED one day, might as well go with whatever gets you the lowest cost!