I haven't liked the same powder in both loads. I like my .357's to bark and my .38's to pop. What I have ended up with as my "standard loads" for my Smith & Wesson 686P 6" is this...
.357 Magnum: Remington 158gr JSP, 16.5gr Hodgdon H110 powder, Remington case, CCI 550 primer.
.38 Special: Meister 158gr LSWC, 2.9gr Hodgdon Clays powder. Winchester case, CCI 500 primer.
I have used Titegroup quite a bit in my .38's and liked it till I tried Clays and found it to be more accurate in my gun and it seemed cleaner.
I have just purchased a S&W 637 and have yet to shoot it. I am looking forward to see how my .38 load will work in the 637. I am guessing I may have to tweak it a little.