I have had different colours in the past, red, purple, blue, white (UGH bad choice). Now I have neutral colours. My 10 gallon has lighter browns and my new 25 gal has dark brown with a small amount of black rock in there.
I am sure that the fish will get used to different colours but I also agree with OohFeeshy that after a while you may get tired of the 'special colours'.
Its all a matter of preference, I like neutral colours. If you have a theme in mind go with that.
Lea-Andra