Re: Dark Reeds
the usual thing to try here would be the Vandoren Bluebox reeds. These are pretty much the default suggestion for dark tone. I don't really like those reeds, however. Now, they do last a while and are less messed up by humidity than most reeds, but they don't often play right out of the box and need some adjustment to perform well, and are quite inconsistant. Even after adjustment, however, they tend to play rather stuffy in my estimation.
My favorite reed of Vandoren's are their V16's, which play brighter than the bluebox, yet a little darker than LaVoz in my experience. They also play well when new with little adjustment.
Hemke reeds produce a very smooth, pure sound that is noticably dark. Not quite so dark as vandoren bluebox, but the reeds are very consistant, play well, and respond well. Their main drawback is that they dont' last very long.
Alexander Classique and DC are good reeds that I find very consistant, but take a little while to break in properly. The Classique compares with the Vandoren BB for it's dark tonal colour, but it sounds more sonorous to me and vibrates better (even though Classique 3's are a tad harder than Vandoren 3's).
DCs have the same element of sonority, speak well, are just as consistant, but are a little brighter and broader in sound. They tend to respond better down low than the Classiques (maybe I need to drop a half step in hardness for those, actually) and have the same break-in tendencies. I haven' been able to measure either of the Alexanders for longevity yet, but reviews tend to point to them being somewhere between the Hemkes and Vandorens for that.
If I had to recommend one to you, based on what it sounds like your trying to do, I'd go for the Alexander DC reeds.