I'm planning on going to the Adriatic coast from Toronto next summer. I'd like to land in either Dubrovnik (DBV),Croatia or Tivat (TIV), Montenegro. I also want to visit London and Paris as stopovers for 3-4 days each. I know this can be done craftily with minimal miles but i don't know how. I have United, Delta, and BA miles to spend (economy seating). Can anyone shed some light on the best way to do this for the least amount of miles.

Thanks in advance.