Merchants say city has the right mix.(B SECTION)

Byline: EARLE KIMEL earle.kimel@heraldtribune.com

VENICE -- While this weekend's Sun Fiesta more or less kicks off the peak season for area merchants, the commercial avenues of the island of Venice define a downtown that works all year 'round.

And night and day: While it is a cousin to shopping districts such as St. Armands Circle, Siesta Village and Main Street in Sarasota, downtown Venice differs in that its main streets are at once both residential and commercial.

"A traditional downtown of mixed-use," urban planner Rhonda Phillips calls it.

"I keep thinking it's the perfect case study for what I teach in community revitalization," said Phillips, director of the Center for Building Better Communities in the urban regional planning department of the University of Florida.

"We have always been in favor of the old-fashioned downtown, where you had shops …