There are so many boats that are bigger than a Sunfish: Flying Scot, 470, Sonar and the Lightning to mention a few. Here is the link to the Lightning Class racing association: International Lightning Class
The Lightning & Sonar can be sailed as hard as you want or as delicately as needed. I believe that both come with, or can be rigged for spinnaker sailing but the older Lightnings will be cheaper. If you want something you can actually sleep on you need to look at small keel boats like the Catalina 22' and their competition (which might even include the MacGregor 26', but look for the older models like the 'S' and 'D' models - not the ones with the 50 HP engines.).
Flying Scot's are very nice boats for their size too and are probably better than the old Snipe or whatever. I know that the Lightning has been around for nearly 60 years but it is a good sailor and there are many of them around that will challenge your sailing skills.
Good luck with your choice.