the main reason you want to use the site plan as it's own drawing ( in site mode)
is so you can elevate the lowest floor plan up or down as needed where it'd be according
to the topography of the site.
note: you put the site plan below all the floor plans in the / navigation / model.
while in the site plan
file / drawing options / drawing options /
site options (left click)
check the "box" to left of "building position"
and than fill in the blank area to "right of / elevation offset"
depending on dimension you put in there (+/-)
it'll MOVE the building > UP or DOWN (you check the UP or DOWN button) in relationship to the terrain / grade.
NOTE: it'll MOVE ALL THE FLOOR (together) at one time
there's more to it than explained above.
all I can say it's definitely the way to go and
makes elevating all the floor together much easier.
tip: you "save as" the site from the lowest floor which is usually your basement or foundation plan.
note: after you draw the site plan "meets and bounds" (if you know it which will give
you the site lines) around the lowest floor plan
than than do the save as but BEFORE you delete the walls and anything else, make sure
you do a "building outline" / read up on this in HELP (top right in the drawings and far left in the ribbon of "help")
i'm sure others will give you other ways to do the same thing.
note: do the site boundaries' via the meets and bounds (directions and lengths of the outside of the site)
note: if you plan on doing realistic 3d renderings, you really do need to include the topography and size
of the site / lot.
if you do the building outline, it'll remove all the earth that would have to be excavated and more
and will give you the quantity of earth to be removed. this will come in handy if you do softlist.
softplan / softview / softlist are super powerful tools for architectural design / estimating / con docs / 3d rendering.
it's hard to complete with those designers that use it for all the above.