I am pulling this from an email I sent to myself that had this information posted by another bride. If you recognize it as you, it probably is!
Event Manager/Floral Designer- Personal gift; letter of praise written to their boss (not actually allowed monetary tips)
Limo- $20
Bus Driver- $20
DJ- $20
Live Musicians- $15-$20 each
Officiant- $25 (or a donation to their church)
Cosmetology- $10 per person
Gown steaming- $15 (I think this too depends on the number of dresses)
Photographer/Videographer- Not necessary. I would suggest writing a letter of thanks/recommendation
Remember that it is unlikely (and very difficult for) you will be able to distribute the tips. Place them in an envelope with the correct recipient written on the front and the person responsible for distributing on the back in pencil. Be sure to give them to the appropriate person for distribution at the rehearsal dinner or the morning of the wedding.