Adjustable LR/LA settings
You should be able to change the minimum roads/knights for the Longest Road and Largest Army cards similarly to how you can change the card limit to get robbed or the amount of vp's to win a game.
A game with minimum 2 road LR and/or minimum 1 knight LA would be pretty interesting such that the first person to place a road or use a knight will automatically have it and it'll be contested throughout.
Furthermore, it'd be useful for balancing other sorts of gamemodes. I've been trying out 4 vp games and they're a fun and interesting change of pace, but if I could change the road minimum to 6 or 7 it'd be far more balanced.
Also, it's just a pretty common sense addition. Catan is always a game about changing things up each time, so this just seems like a logical next step
This is a very interesting idea. It could be taken one step further and have a settings menu for all adjustable game settings, where you could see the default settings for all customizable settings and just edit the list to your own preferences, then be able to save those settings to your own preset button.