We used SunWeddings for our wedding and they are wonderful!! They handled everything and have great contacts in the area for all your wedding needs. Check out my pics in my profile and feel free to email me if you have any questions!
We had our wedding in Venice at a public park right on the beach. Maxine Barritt Park has a pavilion that can seat up to 150 people. We had a total of around 50 attend so had plenty of room for the dance floor and the rental of the space was only $300 plus tax for 8 hrs! It also included the use of the beach for the ceremony. You do have to get approval from both Sarasota County and the city of Venice, but they were great to work with. Go to parks and recreation on the Sarasota county website for info on reserving the space (https://parksonline.scgov.net/default.html).
We didn't have a coordinator, but there are several in the area (according to all the research I did last year... we just didn't want to spend the money on something we could do ourselves, and we live in Central Florida. Only 3 hrs or so away for bringing supplies and such).
I would also recommend the Banyan House (http://www.banyanhouse.com/) or the Horse and Chaise (http://www.horseandchaiseinn.com/) in as a possible lodging alternatives. Susan (at the Banyan) and Lois (at the Horse and Chaise) took great care of us and our wedding party. And they are only a couple of miles from the park. I'm pretty sure that she can give you some recommendations for some of the other services available in the area. They have been in the area for several years and have lodged many brides and grooms along the way.
We just did a wedding rehearsal there on July 10th for Amber and Nathan you can visit them and see their fabulous pictures on our face book page, we had the actually ceremony on Siesta key followed by dinner and dancing at "Mattison's 41" they were glad having coordinators by being all the way in Ohio!! Your SunWeddings team Sigrid, Tina and Cristina www.floridasunweddings.com