This has probably already been mentioned, but it would be nice if you could decrease the wait time for new settlers. Everything else I can build more or upgrade to reduce the wait time (e.g. build an extra Mason doubles the rate I receive stone). So maybe the rate you obtain new settlers could be related to the number of houses or how many free spaces you have for settlers (e.g. extra house decreases wait time by 5% from previous value or wait time is proportional to number of available spots).

