The "Butty Buddy" for $150. Goofy name but worth every penny, goes on and off in seconds so you can have a good looking seat that isnt bulky as hell and the ol lady is happy on rides. 16,000 miles and no complaints but my lady is 115 pounds. Not sure my advice applies to the bigger women.

 

While the HD Sundowner is a good seat for rider and passenger, I have to put my vote in for the Le Pera Maverick. It has a nice, low profile (not like the HD Sundowner) and it is particularly excellent for the passenger. My wife can ride all day on it without complaint.

 

My wife likes the LePera Daytona 2-up that we've got. It's not the thickest but apparently the passenger's seat is still wide/thick enough that she's happy with it after a couple hours ride.