I'm like you. There are times when something sounds great initially. But often when that doesn't happen I do the string rotation thing and other tweeks for tone. As far as comfort goes, I can adjust easily it the sound it right (as in my '76, which is the most uncomfortable and heavy--yet still sounds better than most basses). But I let it ride for a 6 months or a year before concluding this one isn't for me.
I have a '64 Pbass that was great to play, but honky sounding. Had '67 PUs in it and I dropped some '62 Klein's in it and Pyramid flats and it went from the worst sounding bass to one of the best. I'm so glad I didn't give up on it.