S/D shares buses with the Boardwalk (and sometimes with the YC & BC too, but that is during "slow" afternoon). We always stay at the Boardwalk so this is from experience of 4 times in the last 3 years.
The drivers will let you off at the spot most convenient for him. This can be at the "normal" stop where folks are waiting to board for the return or someplace else (especially in the morning when he may not be doing a return route to the original resort). The pick up spot at the park changes but normally it stays the same for the duration of your stay. We've been #8 at the MK one year, and #9 the next year. Believe me it is VERY WELL posted. They have to get thousands of folks out of the park at closing.
Sometimes you will swear that Disney Transportation prefers another resort more than yours, since their buses appear to come more frequently.
In most cases S/D is the last resort on the way back from the park.
Remember there is NO Bus to/from Epcot & DHS. You can take the boat or walk. Also if the DHS is open, it may be faster for you to catch the bus from MK or AK to DHS and walk to the S/D. (it really is a nice pleasant quiet walk)