LorneL .... I have double box and use 2 decora switches side by side. The double receptacle cover you mentioned will work fine. Its a tight fit in the box and care needs to be taken when tucking the wires in.
(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)---(http://www.bdshost.com/X10/lpup.gif)----KDR