ContinentalFan, yes I checked the website. I've found, though, that airport websites tend not to advertise off-airport parking too heavily as many see those services as "competition". Of course, if everyone tried parking at the airport itself, they'd run out of room.

Rkkwan, thanks for confirming what I was beginning to suspect. I was hoping there were some cheaper options, because I found the rates quite high. It seems rates are cheaper at many of the bigger airports.

Just to summarize (maybe helpful for someone):
Pre-Flight Parking: $12/day; $10.80/day after coupon
http://www.longtermparking.com/COUPO...flightpvd.html

Post Road Airport Valet: $14/day regular rate; $12/day rate listed on site; 15% coupon (off of $14 rate??) on website
http://www.airportvalet.com

Thrifty Parking $15.95/day; 10% off coupon on website; 15% AAA discount
http://www.longtermparking.com/COUPONS/cpthriftypvd.htm