I have the Raynox DCR150 and DCR250. And I have used both on my 55-200mm lens.
Optically and price vs. performance-wise I have only praise for these lenses.
The DCR250 is "extreme" at 200mm and will give you a lot of magnification..the kind you might want for a close-up of a fly's eyes or something like that...not a whole flower, for example.
In my experience, I've found that the DCR150 is the one that I typically reach for , but if you're anything like our esteemed GMAZZA and want to get so close to a spider that you can see if it's happy or sad by it's facial expression, then maybe the DCR250 is for you.
As with all macro-photography, the challenge is to get the depth-of-field wide enough to cover the subject appropriately. So the lenses you put these Raynox attachments on doesn't have to be large-aperture lenses - you will most likely require the F-stop to be at F8 or even higher - F11, F16 or something like that - which means you need to have a lot of light on your subject. Sun or artificial lights. The reason I bring this up is that these higher F-stops are usually where most lenses perform at their best anyway, so that Raynoxes can turn any lens they fit into a well-performing macro lens in all but the most unusual circumstances.
Good luck with your choice!