For several years we've had a garden table that consists of a metal
frame (which seems to be of high quality --- no signs of corrosion)
with a three-strip wooden top: solid down the sides, and with square
holes and tile inserts in the middle. We put a garden table cover
(box-shaped tarp, basically) over it for the first winter, and it
trapped humidity and made the top mouldy, so I sanded & varnished it,
& left it open the next winter. The side strips are still intact, but
the middle one (because of the inserts) has rotted through in places.

I thought the best material to use for a replacement top would be
decking boards, because the table sits on the deck which is about the
same age & in great condition, but the planning committee doesn't want
the table to look like some fool and/or cheapskate has covered it with
decking.

Suggestions?