I had to look... (just at Sunday games)
You had some division rivalries -- Sox-Yanks, Cards-Cubs, Reds-Brewers (?), Rangers-Mariners
You had some good sort of regional matchups -- Phillies @ Orioles, Guardians @ Jays, Angels @ Giants
And you had some good (or recently good - Astros) teams who draw well playing at home -- Dodgers, Braves, Astros
And to put that Sunday total up close to Sept 28, 2008, you had a double-header in Minnesota. (That's like Newman's half-full mail truck going to Michigan for Mother's Day!)
Oh yeah, and you had the baseball-est of all Hallmark holidays -- Father's Day!
The numbers:
NYY @ BOS 36,718
STL @ CHC 39,118
PHI @ BAL 44,525
TBR @ ATL 40,211
MIA @ WSH 27,003
CLE @ TOR 40,043
SDP @ NYM 31,454
DET @ HOU 39,199
CIN @ MIL 41,676
PIT @ COL 40,422
LAA @ SFG 41,008
KCR @ LAD 52,789
TEX @ SEA 45,584
CHW @ ARI 37,694
OAK @ MIN 33,835 TOTAL 591,279
OAK @ MIN 20,787 TOTAL 612,022