There are no direct buses from one resort to another. Resort to resort is always going to be a two-step (or more) process. With the bus system, you'll have to use a theme park or Downtown Disney as a transportation hub of sorts. This makes it a balky and inefficient transportation system.
You have two decent alternatives. One is to take a taxi. Efficient, but not free. The other is to plan ADRs around your park touring. For example, if you plan to eat dinner at Boma one night, plan to tour Animal Kingdom that day. Once done at AK, take the short bus ride to Animal Kingdom Lodge. That'll at least make getting there somewhat painless. Getting back to your resort will necessitate the two-step process I mentioned earlier -- a bus from AKL to a park that's still open at that time of night, or else a bus to DTD, and then to your resort from one of those places.
Same idea of you plan dinner at 'Ohana. Plan your day at Magic Kingdom and at dinner time take the monorail or boat to the Polynesian. You could also spend that day at Epcot, take the monorail to TTC, and then walk from TTC to the Poly.
I could go on and on, but you get the idea that it's best to plan your park touring around your ADRs if you want to spend the least amount of time on Disney Transport.