This really depends on who is to attend or what you hope to accomplish.
I have hosted several Tournaments for a previous company that I worked for and we had employees and vendors attending. With that said we setup sponsorships from the Vendors which paid for Give-aways for participants. Turn out was always good so everyone went home with at least a $25 gift card.
Putting Contest and Hole in One Contest are always a big hit because the return on someones money is huge. Here is a good website for contest like that.
http://www.hio.com/hole-in-one/Other options are what have been mentioned so far. Closest to the Hole, Longest Drive, Skins, etc. We would actually allow a "Throw" on the front and back. You could use it anywhere as long as the ball was on the fringe or out. It was to be considered an extension of your last hit so you would not be charged a stroke.
Other than that you want to spend as little money as you can. I do not mean go "Cheap" either. If you do that no one will want to come back the next year. What I mean is shop shop shop, do not buy the first thing you see in the first store. When you are buying prizes tell the store owner what you are doing and tell them the amount of money you have to spend. They WILL give you discounts so take advantage of this. Also, shop around on the net. I know alot of people like to buy local but I had an instance where the trophies I wanted were $18 each locally, however I was able to find them for $9 online with no taxes and no shipping.
These are a couple of websites I have used. I highly recommend them. (Actually waiting on 380 Trophies from TrophyDepot.com for our Little League Season).
www.trophydepot.com
www.pargolf.com
Last thing I will tell you is Golfers like getting free stuff. A goodie bag is a HUGE hit. Sleeve of balls, vendor sponsored hat, golf towel, tees, divot tool, etc. Any of this stuff would go over great. Trick here is to give this to the Golfers before they set foot on the Course so they feel like they have already won something. I have found it keeps everyone in a good mood for the most part.
OK, really one last thing. STICK TO YOUR GUNS!!! You make the rules and make no exceptions. There will be people that try to take advantage but you cannot let it happen. 99% of the participants will have a good time and follow the rules but there is always "That Guy". Handle those issues swiftly and the others will appreciate that as well. Trust me, its hard, especially when that 1% was a VP, 2 Directors and 2 Managers for me one year.
Hope it goes well. Its alot of work but very rewarding at the end of the day.
Daniel