I've recieved some old chairs that need to be refinished. The wood is
real porous and rough. They've been dipped as well.

I'm concerned with it being too porous/grainy. The whole chair is
rough, not just a few spots. Should I just sand this until its smooth,
apply some kind of filler, or try to fill it with coats of poly? If I
sould do the filler, what is the most painless method?