I think House Rules are good but I'm also quite bad at sticking to them unless they are forced on me. I was thinking maybe Holland --> Netherlands with only being able to take provinces I have a valid claim to and no vassalising outside of my culture group? Also no PUs.
Also only demanding the release of other netherlands/belgian nations to stop me balkanizing the blobs.
Thinking about this more I really like it. Haven't played Holland in a while so think I'm going to polish my rules and do this.
EDIT: Ok so my rules are,
1. No taking provinces without a valid claim (core, same culture, other reasons I deem valid).
2. Only vassalising countries I have a valid claim on e.g. Utrecht yes, Hansa no.
3. Switch to a republic at the first opportunity and never change to a monarchy again (mostly to stop temptation from PUs and HRE).
4. Once I gain a CoT, aim for full mercantalism and only trade in my CoTs, free to do as I please beforehand but must not purposely avoid gaining a CoT.
5. No colonising.
6. May not demand release of other nations unless they are provinces I feel I have a claim to OR they are crazy provinces I don't feel they should own. e.g. France owning Finland but nothing in between.
7. May demand release of vassals if they are not in the same culture group but otherwise not.
The last 2 are mostly to stop me removing France as a threat in one war, I may break those rules if I feel one country is becoming too powerful to the extent that the other AI can't compete. I am unsure on lucky nations but overall I dislike the mechanic so may turn it off.