If you want increased comfort you may have to give up a little consealability but not much.

Check out Hogue offerings:

http://www.hoguestore.com/index.php?main_page=index&cPath=27_61

or

http://www.pachmayr.com/revolver-grips.php

For general practice and plinking use .38 Special. Save the boomers for limited practice and SD. Guns don't have to be brutal to the user to be effective.

I got the non overmolded (they were cheaper) Crimson Trace grips (you can see them in my profile picture). They are smaller then the originals, very, very comfortable (the original grips would make my hands bleed after about 50 rounds of .357) and the laser does amazing things for the SP101

Brownells sells the monogrip thats thicker and for larger hands here. http://www.brownells.com/.aspx/sid=1...1_?mc_id=10000 But any larger grips are more likely to print compared to the smaller originals.
If you like wood, I use to have some Badger grips that felt pretty good and looked great here. http://www.badgercustomgrips.com/rug...ips.php?page=1
I liked the concealibility of the original Ruger grips with the rosewood inserts, I ended up changing the inserts out with some stag inserts which is what I have on my GP100. It does grips a little better because of the rough textured recesses in the stag.