I dislike the majority of pre-made Maxis characters.  Therefore, I prefer to use the empty neighborhood templates created by SaraMK combined with various nospawn hacks from J. M. Pescado.

If you want more attractive maids and nannies, killing them off is probably not the best idea.  The game will automatically generate new NPCs, all of which draw their DNA from the same Maxis gene pool.  However, if your goal is to create a nice, large cemetery, you may be onto something.   There are a number of tutorials available online, but by using SimPE's Sim Surgery, you can easily change the appearance of Kaylynn Langerak and company.

I absolutely loathe pre-made Maxis townies and downtownies.  If one happens to slip past the hacks and empty templates, they are either killed off by another Sim with one of the many hacked weapon mods or fully edited with SimPE.  Benjamin Long(nose), Ivy Copur, Komei Tellerman, etc. have all been declared "persona non grata" in my custom neighborhoods.

I do not find myself playing the pre-established families very often, but I believe I have killed off (or heavily edited) more than 3/4 of Pleasantview.  I sometimes check in with Veronaville, but the Montys rank high on my list of disliked families.