A lot of interesting replies on here, most coming from a regional perspective about what was popular in their area of the country. I had the good fortune to move around the country quite a bit in the 60's and 70's, so I had a little different perspective on things.
If you wanted to make a living playing Pool in that era you number one had to play 9-Ball! That was the by far the biggest gambling game at the time and like TRW noted it was a much more difficult game back then playing "push out" and spotting all balls. If you wanted to make some easy money, you played Eight Ball in the bars and every self respecting hustler played on the small tables from time to time. When we talked about good "spots" to go to, the conversation might include poolrooms and bars.
One Pocket was the second most lucrative game for pool hustlers back then, offering a big advantage to the more skilled player. You couldn't luck out and beat someone playing One Pocket, which could happen in a short set of 9-Ball. That's why most 9-Ball action back then was either by the game or playing "ahead" sets. There were often situations where a strong local 9-Ball player was vulnerable if you could get him into a One Pocket game. Straight shooting was not enough to overcome knowledge of the game!
On the East Coast (particularly the Northeast) Straight Pool still reigned and most of the money games were in 14.1, usually playing by the game to 125 or 150. That said, the skilled 14.1 players could play all games so it was definitely not a hustler's paradise messing with these guys. Only the very best players tried to hustle pool around the Northeast, the action was just too tough.
In the Mid South states like Kentucky and Tennessee and farther South you could get Bank Pool action, but this was also tough action so you had to pick your spots carefully.
Once again, on the East Coast almost all tables were 4 1/2 x 9, but in the South and the Midwest the over-sized 8' tables were very common. Out West it was mostly 9' tables again. Bar tables were almost universally 7' with one notable exception. In the Northwest they played on 8' bar tables.
I never saw much gambling at 14.1 anywhere, so there wasn't any real money to be made at that game. Same for Three Cushions. It was rare to see a money game. Not that it didn't happen, just that it was a rare occurrence and if you were trying to make a living playing pool, you were looking for action every day and 9-Ball was the ticket. And bar table Eight Ball was second.
So in conclusion, I will say that a serious pool player in that era needed to be skilled in only two games to do well, 9-Ball and One Pocket. So in that respect it was not that much different than it is today.
As for Ten Ball back then, it was the preferred ring game format among good players and rarely did you see a money match between two players at Ten Ball. The only notable Ten Ball heads up match I ever watched was between Buddy Hall and Jimmy Reid, two of the best back then. On that day, Jimmy won (I was in!) and Buddy beat him a time or two as well.
The fact that almost everyone offered there take on the preferred games from their era from their regions has made this thread a very fun and also informative read. Then of course Jay chimes in and gives us all we need to know. I'm a bit of a history guy and obviously a pool player so any chance I get to read up on any old school info or stories or whatever is truly a treat for me so thanks for all who contributed to this thread!!!