You will enjoy reloading. One observation and one question. Observation: the 200 grain Rim Rock DEWCs sit deep in the case, limiting the powder capacity more than other types of bullets, even those weighing up to 240 grains. This is something to consider. Question: how fast do you want to drive the bullets? I highly recommend Trail Boss powder, especially for new reloaders. It meters well through powder measures and is light-colored and bulky, which helps prevent accidentally double-charging a case. Given how deeply the Rim Rock bullet seats, however, you won't get much more than 5.4 grains of powder in the case, limiting muzzle velocity to under 800 fps.
Unique is a classic powder in .44 special. It will drive your RR DEWCs to higher velocity. It generally meters well, and has some bulk. It's only real drawback is that it burns kind of dirty.
I have not decided what I think about Titegroup yet. It burns fast, which gets velocity up quickly in short-barreled revolvers. However, it takes up very little volume making it very easy to accidentally double-charge a case--which will likely have disastrous results. I also found that driving the Rim Rock bullets over 800 fps tended to lead my Bulldog. Titegroup has potential if you want to drive your DEWCs up to 900 fps, but I can't recommend it as a beginner's powder.
Trail Boss is one of the most versatile powders out there. Unique is a classic that can also be used for a variety of applications. I use both of these powders in .44 Magnum as well--Trail Boss for light target loads, and Unique for mid-range loads that are more powerful than .44 Special but less than full-power magnums. Those are the two I'd look at first.