I usually (pretty much always) have a seperate 20 amp circuit for the bedroom plugs on an afci. I will put up to around 10 or so receptacle outlets on this circuit, which is around 2 bedrooms, maybe 3. I wire the bedroom lights on one 15 amp afci circuit, and feed the smokes off this. I loop all the smokes together (bedroom or not) with 14-3 romex. On some fancier jobs there is alot of recess cans in the bedrooms. Now we are talking more 15 amp afci circuits to avoid any overloading. For me I am putting in avarage of 4 afci breakers per house. The curly neutral on the afci breakers messes up my formerly pretty neutral termination jobs.