Never give a timepiece as a wedding gift (or any sort of gift), as it signifies a countdown to the end. In fact, no gifts are expected--just a *red envelope. (*See entry for guidelines)
--Chenluolan
THE gift for weddings is a red envelope with a cash amount that is a factor of two (and 6s are also considered lucky) - Ex. 1,600/2,200/3,600.
Note: The total should at least cover your banquet meal(s), the cost of which varies by city/inflation/etc., so researching the venue can be helpful.
--Chenluolan