I don't have enough detail about how the top is being constructed to
suggest a best method but I can tell you that you cannot stain it using
masking tape and have it come out looking any good. You will get at
least some wicking and probably a lot so it just won't work.
You could pre-stain some Maple and build it into the table but this
is very problematic because you can't sand or scrape it. Your best bet
will be Walnut or some other acceptable material for contrast.Either
built into the table or veneered.
I much prefer solid over veneer but veeneer is perfectly acceptable as
some of the best furnitue ever built uses veneer.
I would probably glue up 2, 14 x 15 Walnut panels. Then make a mortise
across the 15" ends. Then glue up 3 Maple panels 15" wide by
appropriate lengths. Then tenon the 15" ends. Then glue up the 3 Maples
with the two Walunts in between. Then trim the whole thing to 14" wide.
Now you have a 14" wide panel to use at the center of your table top.
Another possible alternative, if you will bread board the ends, is to
do this same process but only use two Walnuts and one Maple in between.
Then glue up the whole table top to width and put wide bread board ends
across each end. This is the only place I would really worry about the
different material expansions and it can jut be handled in the normal
manner bread board ends are done with slotted pins and strategic glue.