Saddlebrook and Newks
My 4.5 friend went to Saddlebrook to knock off the dust and returned with a big grin and lots of blisters. On that little knowledge, I would recommend it.
I go to Newks every winter and the during the week crowd is quite low. Let them know you are coming or ask when there is a group at your level. If you just go with the flow, you will be thrown in with the 3.0 - 4.0 crowd. Let them know you want some serious tennis and they will accommodate. They were sufficiently good to train Ryan Harrison and his brother so think they have the capability for you, you just need to get them to action.
I too would like to give Spain a try and would enjoy feedback.
I am below you BTW. A 4.0 on bad days and 4.5 on good days.