Here's the thing. Any 'ready made' seat you buy is going to be 'one size fits all'. Most seem to love the Mustang seat (myself included! ESPECIALLY with the backrest, heed my advice, whatever seat you get, get the backrest. It can't be added later to the mustang. Get it now, and LOVE it). However, a Russel is custom made. I have NEVER seen anyone be dissappointed with a Russel seat. I've seen (albeit only a few!) people think the Mustang only slightly improved the comfort, or was worse!
My wife actually thinks the Mustang seat is worse than the stock seat. We put a gel pad on the top which helps. Yet she rides all day long on the stock seat on her Honda in perfect comfort, says it's the most comfortable motorcycle seat she's ever sat on. (I've ridden it, I dunno what planet she's from!) But for me? That Mustang is a DREAM and I can truly ride from tank to tank without any more than just a little stiffness.
But anyway, point is, only the Russel is going to absolutely work. But the Mustang will probably work, and if you are going to buy a ready-made seat... the Mustang Wide Touring is the way to go.
Also, if you don't already, get a set of highway pegs and a highway bar. Being able to stretch your legs out on a long trip will keep the blood flowing and actually improve your rear-end comfort. Plus, if you're like me, you'll find your new Mustang seat is so awesome on a long trip you can ride for 270 miles without stopping the first time you ride with it! And then, you get off, and your knees sound like machine guns... LOL. I got my highway pegs shortly after that. WHAT a difference. (Never could ride long enough before for my knees to get stiff!)
"8 But God demonstrates his own love for us in this: While we were still sinners, Christ died for us."
Romans 5:8 (NIV)
2014 Kawasaki Vulcan 1700 Vaquero ABS SE
iPod Connector Kit, Kuryakyn Highway Pegs, Mustang Touring Seat, Marvella's Hitch, Kuryakyn Trailer Wiring Kit, Haul-Master Tag-a-Long Cargo Trailer
2011 Honda Shadow Aero 750 (Wife's)
Memphis shades quick-release windshield, OEM Solo Seat, Mustang Fender Bib, Chrome Solo Luggage Rack
Past: 2006 Vulcan 900 Classic LT