I use a house rule in my Swords and Wizardry Complete game, which is that if you die, no matter what level you were, your next character starts back at level 1. On the other hand, if you swap out your character for another during downtime, they can be the level of your current PC. The purpose of this house rule is to make it easier for me, as referee, to introduce new characters, while encouraging the PCs to diversify their character holdings.
Surprisingly, while people have discussed doing this a few times, no one has yet. Partially it's due to an investment in their characters - I've tried to make everyone feel like they've got a unique thing going on, from our ninja elf woman with a leechman's enchanted claw, to Shithead the wizard and his transparent chest, to Mordechai the Silver Man of Arkhesh (who skin was burnt off by an exploding rocket and replaced with a nanosuit by the soul of an astronaut-wizard) and McGillicuddy the dwarven cleric's crisis of faith. Actually, since no one's died in a while, people may just have forgotten this rule, which nullifies its incentive far more effectively than any amount of poor design does.
As it stands, the PCs were given Jamaica by Governor Hesh last session. Technically it's the "Isla de Naufragio" (Shipwreck Island in doggerel Spanish), but it's Jamaica and we just call it "Jamaica" out of character. The scene was one of my favourite interactions so far, since Jamaica hasn't been surveyed, and Hesh is basically willing to give it away to a bunch of adventurers because it's temporarily-worthless wasteland he hopes they'll make something of. Hesh is this old man, and knighting the PCs involved him hoisting his extremely dull ceremonial blade up onto their shoulders and muttering some phrases before trying to figure out how he can award them territories in Jamaica without knowing what the interior of the island is like.
Anyhow, since four of the PCs are now barons of various parts of Jamaica, and three are knights or dames, and they've all got a fat chunk of change in the bank, it's about time they had retinues and people working for them. You may recall I planned some changes to the XP rules, and I think in a few sessions I'll be introducing them. In the mean time, one of the things I'm going to do is have Governor Hesh hire a surveying and exploration team to head out to Jamaica and check it out... meaning new characters and a new adventure, while their old characters remain behind to help Hesh deal with a slave revolt (which we will also play out). And so the cast begins to expand.
I'm really looking forward to the Jamaica map, though I may have to keep it secret for a while since some of the players read this blog. It also means more background cards. Right now there's a two week break since one of the guys is going to be out of town next week, but that works out well, since is the sort of thing where I want extra time to plan and get things in order.