If you're looking for a nice shimmery chorus that can do subtle in spades, you can't do better than the Ibanez CS-9 (for a budget model) or the Maxon CS-9Pro (for the deluxe model). It's a great chorus that does work very well with a fretless (IMHO).
Another chorus that I would look at would be the Hardwire CR-7 because you get 7 different chorus types to play around with and see which one(s) you like.
I'd also highly suggest you either try these pedals out in your local shop (all three pedals that I mentioned are easily found in most shops) or use (abuse) the return policy and take the pedal home and run it through your rig. If you find that you don't like it, it's easy to return it.
Edit: Or you could just scour Craigslist/the classifieds/other forums/eBay for a used one at a cheaper price.
Another chorus that I would look at would be the Hardwire CR-7 because you get 7 different chorus types to play around with and see which one(s) you like.
I'd also highly suggest you either try these pedals out in your local shop (all three pedals that I mentioned are easily found in most shops) or use (abuse) the return policy and take the pedal home and run it through your rig. If you find that you don't like it, it's easy to return it.
Edit: Or you could just scour Craigslist/the classifieds/other forums/eBay for a used one at a cheaper price.