I personally do not hold hands during the praying of the Lord's Prayer.  I do put my hands into the position of the Jewish prayer of supplication [hands close together open and held up---at shoulder height].  I feel that this is appropriate gesture since We and I are/am asking God for many good gifts---both physical and spiritual.  The Lord's Prayer is a composite prayer of praise and a prayer of supplication/asking.  I do shake hands during the Handshake of Peace.