Make it last an entire month, make more interesting rewards and make the highest tier a maximum of 100,000 crowns spent, rewards can be exclusive items sometimes (nothing pay to win) but stuff that will be interesting enough for people to buy, make every tier worth getting so people can be satisfied after stopping at any tier. The month long time period will give people PLENTY of time to get it instead of just a week or so and when the month is over you can make a new list of items with maybe different tier pricings (I still think it should never go higher than 100,000 crowns, but maybe sometime it can be 60,000 for example)
Plenty of free to play games (which i wont name) do this and it can work out well enough where most people wont have an issue with it, KI gets more money for the game and players get more stuff along with whatever they buy with their crowns, its a win for everyone
As for new items being added to certain tiers, i understand not every month KI can create completely new stuff, so i think special exclusive recolors of mounts or pets would be really cool, maybe with a cool looking aura, etc
Please give me your thoughts on this, while the recent crowns event was done poorly, i do think there is potential for a good lasting crowns event system for this game