TripIt has what you seek. It won't do award itineraries automatically, but you can manually edit the price field to reflect whatever dollar amount you think your points are worth. I just X them by 1.43 and enter that.

It has some limitations like only repricing the same flights, and only 60-90 ish days in the future, but it's better than nothing. What you really want is for the tripit alerts to remain silent. I tend to only buy very low sale fares, so I rarely get a re-price alert.

Southwest doesn't pay ball with people scraping their website for free, but it's incorrect to say that they keep their fares a secret. Anyone with access to the airline tariff database can see them. The fare watch sites all have it, plus you can peek as a individual user on Experflyer or certain travel agency portals. It is kind of odd in that you can view their fares in many places that can't sell you a ticket, but that's Southwest.