clay soil = worrying about drainage. Any hollows will be very wet after heavy rain. Run-off will be more significan, so the shaping around bnkers needs to be more careful to prevent wash-outs. This can mean that 'gathering' bunkers aren't possible. Clay compaction can result in very firm (ie hard) fairways, resulting in less controllable bounce and more run, especially when the fairway is allowed to dry. It can also play incredibly slow (hit and stick) after heavy rain.
sandy soil - freer draining, better combination of air and water possible. Less of the above issues.
Merion East is an example of what can be achieved on clay, with good design and very good maintenance.
James B