This is an old thread, but I'll put my opinion in. When looking for a Mustang, I only wanted a coupe. I had driven both convertible and coupe, but I like the lines of the coupe MUCH better than the convertible when the top is up. But for me, it matters a little less since I already own a 1998 Pontiac Firebird convertible (red, still looks new). So I get my convertible fix whenever I want it. Also, riding motorcycles gives you a wind in your face fix, too.
2013 Mustang GT Premium (6 speed manual, 3.73 gears, GT500 axle-backs, no resonators), 1998 Pontiac Firebird Convertible, 2003 Jeep Grand Cherokee, 2007 Honda ST1300, 2001 Ninja 250