Tipping!!! This confused me too for the longest time. The general rule of thumb is you tip people who work for a company but not those who work for themselves. So if your DJ owns the company, then no do not tip, but if they work for some company (and thus aren't actually getting all of the money you are "paying" them), then yes you should tip. As for the wait staff and bartenders, their is a 15% service fee added to all the food and drinks so I would not tip the bartenders or servers (unless they are exceptionally good!).
I'm planning of tipping the wedding coordinator (personally I'd say a few hundred...), guitarist (maybe $50... depends on how good he is :-P), person preforming the ceremony (again maybe $50, we're a symbolic non-religious ceremony so it will be short and sweet, if it was more complex I'd probably tip more). We're flying our photographers down with us (it's actually very cheap because their trip is their payment!) and they own their own business so no tip needed, but most hire theirs through a company so I'd tip a couple hundred to them if they were with you all day and did a good job.
This is what I've been thinking anyways.... I am a little scared that I'm being too cheap...