Been considering the idea that the current system allows for some specialization of cities, so my newest trade route idea
Each trade route is either
Production (internal)
Growth (internal)
Energy (external)
Science (external)
[or Station or Outpost]
internal routes could be mirrored
The benefits would be
Production (internal): Receiver gets 20% of senders base production
Growth (internal): Receiver gets 20% of senders (base food - consumed food)..minimum of 0
Energy (external): Sender gets 10% of sender base energy + 5% of receiver base energy... Receiver gets 5% of sender base energy + 5% of receiver base energy
Science (external): Sender gets 10% of sender base science + 5% of receiver base science ... Receiver gets 5% of sender base science + 5% of receiver base science
Stations give 4, 8, 20 yield instead of 4,6,10
For UI,
The previous trade route would be displayed at the top of the list and could have an 'auto-renew' option (which you could go into the maintrade route screen to switch off)
If you selected a specific Type of route, the yields would automatically be organized from greatest to least (all internal ones would have the same yield, but external and station ones would not)
Autoplant options are
+1 trade route in cities over 15 pop
OR
+5% Production, +5% energy, Free autoplant in all cities
cost of autoplant doubled