If the two saws are not going to be used simultaneously, then their
placement relative to each other isn't very critical as long as the
table heights and fence positions are compatible. I'd position them as
close together as possible without causing the structure of either saw
to interfere with operation of the other.
Position along the bench is a little more difficult to decide.
Assuming the walls are a limiting factor - no windows, doorways or
other openings aligned with the bench - I'd give serious thought to
the type of work that you will be doing and try to make a reasonable
estimate of the longest rip cuts you expect to make. Position the RAS
such that it's no closer to either wall than that dimension plus
whatever clearance is comfortable for you. Likewise, try to estimate
what the longest workpiece and/or offcuts you're likely to have to
accommodate with crosscuts on either saw and position the saws
laterally so they will accommodate those lengths. A location near the
center will probably, repeat probably, give you the most flexibility
for crosscuts and will maximize the length of rip cuts that you can
I can almost guarantee that whatever lateral location you choose,
eventually you're going to run into a case where you simply cannot put
the cutline under the blade without punching a hole through the wall.
Have a couple of sawhorses and a circular saw or handsaw available to
handle it when that happens.