I just did the vinyl tour in DC and SF; not enough time to visit all shops or contact dealers, but here's my report:
DC shops:
best was JOINT CUSTODY on 1530 U str., recently opened, good selection, 2 boxes with some appealing 45s from 5 to 30 USD, some nice comps, all viny, worth a visit
SOM records, 1843 14th str.: no 45s , and few comps, but guess what I bumped into KID CONGO POWERS who works one day a week in that shop (see selfie) , a real cool good humoured dude, we chatted for about 20' and had some good laughs, he still tours and records with his groups THE PINK MONKEY BIRDS and is still in contact with Krystie aka Poison Ivy
SF shops:
AMOEBA, 1855 Haight Str: pretty vast selection of comps both vinly and CD
RECYCLED RECORS, 1377 Haight Str., all Vinyl LPs, a bunch of not really rare comps, but well selected
ROCKY RICARDOS, Haght Str. , all 45s, primarely Soul, no garage
The big low down was GROOVES on 1797 Market Str. unless you are happy to forkm over 1o USD up for Beatles/Beach Boys/Stones singles....all boxes badly selected, very few 45s, mostly LPs, mostly trash

unfriendly vendor (not Ray Anderson), a waste of time ('except for the nice window)
all in all, I bought 6 + 4 nice

comps, it really seems that nothing can beat Internet auctions and mail vendors, I'm sure record shops have had their days...
anyway, I'll be in LA for the next days to check out more shops, so stand by for part II of my report!