I'm a bassist. I played original music from 1982-94 mainly in the Philadelphia area. I've recorded a few albums in bands and as a session player. Here's some of my solo work.
http://www.myspace.com/basqueindigo
http://www.myspace.com/servorex
I was a staple at a club called the Galaxy in Somerdale N.J. back in the mid to late 80's and early 90's. I've played all of the Philadelphia area night spots from back then as well. The Galaxy was the musician's hangout. If you made it there, you were good. You had to be.
Anyway, I've been playing fretless bass since 91. I strongly suggest not using flatwounds. I know round wounds tend to dig into a board but that's the way it goes when you go fretless. You never want to limit your ability to add tones to your tool box. Flatwounds take away lots of treble. This is why the guitar gods gave you a tone knob. Roll it off and you have no treble. If you don't get any flexibility then you need to expand to a 500k pot. Where your plucking hand is matters too. If you're back by the bridge, high end is brought out. up by the neck you have instant upright if you also have the front pickup on.
The goal of playing bass is to get what ever sound you need on the fly. All things are possible if you know how. There's always a way.
Effects: Tremelo is good, Wah, Chorus, Compression, and my favorite the Octave under with the bridge pickup on and the tone rolled back about 10%.
You want to hear the best bassist ever check out Jaco on you tube. He's impossible. He also got the upright sound out of a 62 jazz with roundwounds.