Here are my two cents
MK - Monorail from Poly is the quickest. The Ferry is a neat ride but it will take longer! So go ahead and take it if you have some time to relax & enjoy the ride (usually best leaving MK going to the Poly)
EP - Walk to TTC and take Monorail
AK - Bus (don't go on early morning days)
HS - Bus
DD - CAB! The bus takes forever...
BB - Bus
TL - Bus
Other tips:
You can walk to the Grand Floridian or take a quick monorail ride. I like to walk around and shop there. Or you can have tea (or young ladies can do that with Alice in Wonderland!)
Take the monorail to the Contemporary for dinner then you can walk to MK.
Enjoy the Boardwalk after Epcot one day (or before!). Take the monorail to Epcot, walk to the back "International/Hotel" entrance/exit and walk to the Boardwalk or Yacht/Beach Club. You could also take a ferry to HS from the Epcot hotel area. Then you could take a bus back to the Poly from HS. If you don't go to HS, go back through Epcot and take the monorail back to the Poly. But this is a lot of travelling & walking so only do this if you are ready for all the walking (remember, Epcot is REALLY big).
Sometimes, the bus rides back to the hotel can be exhausting, especially if you have small kids. If you want to spring for a cab, that's fine - it's your vacation!
Have so much fun!!!