Given your height and inseam, I'd think that 24.5 would fit you much, much better than a 23.5. I'm 5'11" with 32-33" inseam, and I like a 24" best. I have a 23" and it is a bit tight. BUT, you really should go visit a bike shop and stand across a few frames. Better to ride a few.
Good luck. And Welcome!
LL
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1959 Hilton Wrigley Connoisseur (my favorite!)
1963 Hetchins Mountain King
1971 Gitane Tour de France (original owner)
* 1971 Gitane Super Corsa (crashed)
* rebuilt as upright cruiser
1971 Gitane Super Corsa #2 (sweet replacement)
1980 Ritchey Road Touring (The Grail Bike)
1982 Tom Ritchey Everest
(replacing stolen 1981 TR Everest custom)
1982 Tom Ritchey McKinley (touring pickup truck)
1985 ALAN Record (Glued & Screwed. A gift.)