The rule of thumb is to tip service people but not professionals and those who own their businesses. People usually seem to tip the officiant, even though s/he owns the business and is keeping the entire fee you're already paying. A gift or gift card seems to be the preferred tip for a planner.
There are lots of resources online for how much to tip, but it's hard to find consistency among them. This is what I've come up with:
limo driver: 15%20% (a little tough to calculate when the service is part of your package... maybe $40?)
violinist: $15$25
officiant (if no fee is charged): $50$150