Good evening Linda,
If you are worried about retaining value and are willing to spend between 4-7 million, perhaps you'd like to consider Isleworth or Lake Butler Sound, or Keenes Point in Windermere.
In the range you mentioned, I too would be wary of property owners who share the same lake. If some of the docks are badly maintained, or if the lake isn't patrolled by the county to protect against irresponsible boaters (drunk driving etc) , Another possibility closer to Oviedo would be in Winter Park , perhaps Windsong or in the Vias.
I believe both the Winter Park Chain and the Butler Chain are patrolled to protect safety and cleanliness while using the lakes. There are homesites available on both and some beautiful recently built homes that are aggressively priced even for this market!