S.E.
Either is fine but if you go with the gift either give it to them prior or after I would not take it to the wedding. You could also have it sent to them if you buy the gift on-line. Most receptions just have a small table with a card box on it but that is the weddings I have been to.
I actual prefer to give a gift over money because it is more personal. I am just not a fan of giving money but that is me.
S.