Mike, I agree with the wet sanding. I have wet sanded with 600 wet/dry paper with Watco. Will work well on an open pore wood like oak and walnut. Fills the pores and makes for a real smooth finish. I agree with the problems you described with pine. I have used Minwax sealer on pine with some success. It still left some blotches when I stained it, but it did even out the finish for the most part.
