We've always used the buses and never had an issue. Each resort has a main bus stop (or more than one depending on the size of the resort). For example, the GF has one bus stop and POR has a few stops. (I don't remember how many though)
Each bus will have the park name listed in the front window of the bus. The buses "usually" run every 20 min or so, depending. But they're pretty frequent to each park. So you'll go to the bus stop nearest your building (or if you stop to get coffee first, you can get the bus at any other stop at your resort). Then you just kind of sit and wait for "your" bus to come. Once a MK bus comes (and you're going there) you just hop up and people kind of form a line. They let people off first, then you get on. It's super easy.
At each park there's a "bus station" and the station is clearly listed which resort the buses are going to. You'll get off your bus there and walk (short walk) to the main entrance. When your day is over at the park, you'll go back to the "bus station" and find your "bay", marked for your resort,and pick up your bus there to return back to your resort (or wherever else you're headed). If you are at AK and want to go back to the MK, you can hop a GF bus (or one of the other monorail resort buses) and get off at the GF and then hop the monorail to MK.
Now, what people refer to when they're saying they go to the TTC, and all that jazz... if you're going to have a meal at one of the monorail resorts, you can hop the monorail or take a boat right from the MK. You would take your resort bus to MK, then get on the monorail or boat to the CR, Poly or GF (or WL). If you want to go from MK to Epcot in a day, you could hop the monorail to the TTC and get on the Epcot monorail. Or take the ferry / monorail to the TTC to pick up the AK or HS bus. (does that make sense?)
Personally, we've never felt the need to drive to any park or take a cab. If you just have a little patience, the Disney transportation is fantastic, and will get you to your destination without the hassle of having to park / walk too far.
The other thing is, if you're at Epcot, you can also catch a boat to the Epcot resorts or to HS. It's really convenient, actually. But all of the buses are clearly marked as they're coming through your bus stop, so you shouldn't have any issues getting one to a park. They can get crowded during peak times, so you may have to stand. But it's really never that long of a trip from a park to your resort, so I've never really thought it was that big of a deal.
Once you check in, they'll give you a resort map so that you can see where the bus stops are at your resort. Then you can have some idea which is closer to your room or the main building.
I hope this helps a little!
Have a great trip!!