The guys above hit the nail on the head; in general, casting for heavy lures and spinning for light lure. At the end of the day it all boils down to preference, just make sure the lures you're throwing are rated for the rod you're using.
$500 Casting Set-up:
Shimano Expride: 6'10 medium fast
Shimano Chronarch MGL (7.1:1)
$500 Spinning Set-up:
Megabass Orochi XX: Whipsnake
Shimano Vanford 3000 HG
$400 Casting Set-up:
Megabass Levante: Jerkbait Special
Daiwa Tatula SV TW (7.1:1)
$400 Spinning Set-up:
Daiwa Tatula Elite: Meyer Finesse 7' ML Fast
Daiwa Tatula LT 3000