Boots provide protection from engine heat and keep your ankles safe from low flying rocks. They need to have non-leather soles so you can maintain firm contact with the ground when holding up your bike and still be comfortable to wear. I like buckles on the outside sides of the boots. Some boots have buckles and emblems on the inside sides. Avoid such buckles because they may scratch the finish of your ride.
On July 1, 2009, I bought my third pair of motorcycle boots. They are H-D black Ransom boots. They have lug soles (with an ugly orages in some spots), zippers on the inside sides and a nice buckle on the outside sides. Size 7.5. Price was $152.99 at San Jacinto Harley Davidson in Pasadena, Texas.
For some links about buying boots, explore the listings below.
"Crash Padding - Part One: Suits, Boots, & Gloves," by David Hough
"A Few Tips on Harley-Davidson Boots," by Custom Chopper Guide.com
Zappos.com has pictures of most Harley boots for men and women.