I consign at several Chaos NPC and player shops. Most notably Clearport (connie and Tavern) as well as NT. In addition I stock a couple of guild only connies. The reason I stock "a lot of stuff" is for my own use and minimize interruptions to my game play for minor items. I can simply referr people to the appropriate connie/tavern.

I would like the options to consign for 4 week. This would cover most times that I am on the road and don't have ready access to the internet.
So my preference is for a 4 week option, or when consigning to have a 2/4 week option with corresponding charges.

I am against the forever option as it would tend to clog up the connie.
After the consignment period my preference is for the items to drop to vault as I tend to overstock items so that there is only a small chance that items (generally potions and foods) run out. Even though I "overstock" in general, from time to time Strength V, Metal Reapers or other items do sell out.