Love the personalized water bottle idea! One thing I learned when I did this for a work event is that the ice melts quickly--- and when ink and water meet, there goes your pretty labels! You may want to use ice packs instead, that way you won't run into this problem.

I had a friend get married outside last year, and since it wasn't in a church, she could do all sorts of fun things. She had chilled champagne served to all the guests as they arrived, making it feel like the celebration was starting right away. That was cool. You could also serve lemonade or something non-alcoholic.

One other thing, have music playing the entire time. Since you're outdoors, it'll pull the environment together and create a nice ambience for the area. Guests will feel relaxed and like they're at a formal event.

Have fun and wear lots of deodorant!