I also had a Madison area wedding, and wanted outdoors as well. My wedding was a vintage theme (something you might appreciate!), so I actually moved it about 30 minutes outside of Madison, to Columbus. The reason was the venue: a gorgeous, historic ballroom with beautiful huge windows, a stage (for the DJ), and a beautiful park with a stream.
We rented white chairs from the nearby hardware store, and all my girls and I had brunch and got ready a few blocks away at the Columbus Carriage House B&B. The owner was wonderful, and even let us finish assembling bouquets, do our hair, and get ready in the parlor and our rented room. Then, we all met up and everyone headed over to the Fireman’s Park (site of the gorgeous ballroom and our outdoor ceremony.) My dad and the two kids (RB/FG) took a horse and carriage over to the park. Bonus: $350 was the rental for the entire day, plus we could have our own bar AND caterer! It included tables and chairs- we just needed to rent linens and do the work ourselves.
We had a harpist- cheaper and just as great a sound as a string quartet. Rachel Avery in Madison was wonderful and even arranged a couple songs just harp, just for us. (You can Google her and she pops up.)
Other vendors: cake- Carl’s Cake was the bestest.
DJ: http://www.msldj.com, Eric Fischer is one of the best DJ’s I’ve seen. (And I’m a wedding photographer, so I see a LOT of weddings!)
Flowers: DIY with http://www.flowersandfreshness.com. Very inexpensive way to do flowers if you or any of your girls are even a little bit crafty.
Photographer: A good photographer friend of mine is Mandie from Red Gecko Studios, or you can check my profile for my website. 🙂
Hmm, that’s all I can think of right now, but if you have any more questions. I do see quite a few weddings so I have lots of great resources/contacts.
Oh, and another option for outdoors: The Gundry House in Mineral Point, or Olbrich Gardens in Madison, or Allen Centennial Gardens in Madison. Good luck!