Turn Back the Clock - Ticket Prices - Have one game mirror prices from a recent season of significance (1984, 1998, 2003, etc.). It could be a crappy mid-week April game for all that I am concerned
Turn Back the Clock - Bleacher tickets on sale day of game only for one or two midsummer mid-week day game(s). Some of my favorite Cubs memories were waiting for gates to the bleachers to open. (Season ticket holders would obviously still have seats)
Turn Back the Clock - Concession pricing - Have pre-game concessions (beer excluded) return to prices from a recent season of significance 1984, 2003, (This could apply to some Thursday day games)
Promotion and Giveaways - Have 20-50 Jerseys and historical Memorabilia from each year given away via scratchers (similar to jersey giveaways from recent years)
Promotion and Giveaways - On the Day the stadium turns 100 years old - Have one of the nicest commerative stadium giveaways of all-time to be given away to the first 1914 fans (and another 1914 to be given away via scratchers) I am talking something that costs around $50 to make.
Turn Back the Clock - Jerseys - Have each Sunday game be a different historical Cubs jersey
"1914" family promotion - For certain games, for $19.14 you can get a ticket (i.e. UD reserved - Outfield) a hot dog and a drink, with a program for the group of tickets - need to be available in sets of 3-12.
Feel free to bash, add, or modify. None of these are too costly (with the exception of the Stadium giveaway), but they all would appeal to fans.