The only "organised/group" tours I've ever done have been with cycletouring clubs. Cycletouring clubs usually have day rides, weekend tours, and one or two longer tours. You pay your membership fee and ride as many day rides with them as you want. Some weekend tours might be included in that price too, although you might have pay your own accommodation for some. And for the featured tours, there is usually a fee which will cover the accommodation, food, sag support, etc.
The cycletouring club I rode with was the Elbow Valley Cycling Club in Calgary, and I did two Golden Triangle tours with them, and one Logan's Pass hub-and-spoke tour. The organisation and support for all was wonderful ... very well done. And the price was slightly higher than I would have paid to do it myself, but then, I probably wouldn't have eaten as well or been as comfortable.
None of my other tours have been "organised/group" tours.