As the mom of an almost 8 month old, I would say you can never have enough burp cloths. We started off with probably about 12 and have built up to somewhere around 20. My son was definitely a spitty baby, so we may have used more than normal, but even today, I always have one in my purse, just to wipe his face (drool) or in case we have a spit up on the go. Also, while there’s some really cute burp cloths out there, I would recommend just getting the packs of flat cloth diapers at Babies R Us and using them as burp cloths. Not as attractive but WAY more absorbent! (FYI, I’m a working mom and can only do laundry 1-2x a week, so my number may be a bit high but even home on maternity leave, we went through burp cloths so fast!)
As for the others, in my experience:
Receiving blankets: One pack (4) of the Aden + Anais muslin blankets was plenty for us. We transitioned to the SwaddleMe wraps very quickly. Definitely get 1-2 very large blankets for the floor. We use those all the time now.
Hooded towels: We got a ton as gifts, but tend to use the same 2-3 all the time with no problem.
Washcloths: A pack of 6 or 8 would be plenty. Though we tend to use them a lot now to clean him up after mealtimes. He’s decided he wants to feed himself, which is cute but very messy!
Bibs: We probably have 30 (tons of hand me downs), but I would think 8 would be enough. Bibs are something you can wait and see if your baby is a spitty/drooly baby.
PJs: He slept in the gown-type pjs for the first 2 months. I think we had 4-5 of them. Babies have a lot of middle of the night explosions, so it’s helpful to always have a spare clean one!!! Now that he sleeps in regular pjs, we have about 6 pairs. (But again, I am only able to do laundry 1x week, so that may be more than you need.)
Bottles: My son is 100% bottlefed now, so we have 8 bottles. But if you are planning to b’feed you only need 1 or 2 in the beginning. My husband did one pumped bottle every evening, so we got by with 1 bottle for a while.
Hope that helps! Let me know if you have any questions. There are definitely a few things I would have changed about my registry in hindsight.