Hi INLAK !
I'm on the "newer"
RJ stuff, but this is what we basically have.
Usual flap setting is 18. This, most of the times, gives us (?) a better coverage of the 2nd segment which is mostly limiting. In some place, such as the infamous ZRH northely SIDs, you have to use 18 for noise abattement. Strange enough, we are some times better using flaps 24 and sometimes better with 18 using the same runway and conditions, but don't ask me, I sure didn't write that perfbook (called ODM in our company). Seems it should be based on the BAe WOT tables, but is sure doesn't make sense, at least not all the time
Nevertheless, another rule, if not overriden by another one (see everybody, this is why aviation as whole is sooo complicated....
) is that when heavier than 37T, flap setting is 24. Now, slippery rwys, ice etc, will have to be dealt with fl30.
As for LCY/LUG/SIR and similar places, we can use up to 33.
Initial climb perf? Yeah, well, like in LCY with 33 it is just a matter to be jumped airborne and then retract the dangling stuff. Fl24 gives you better initial obstacle clearance, but once more penalizes you later.
All this of course based on my modest experience of this pleasant little bird
