I would agree that you need to get on as many boats as possible to start getting a feel for what you want. One great way is to look for brokerages in the area having an open boat day. There is one near me that does that almost every Sunday I think, and I think it is usual in other places too. Basically its a day when they open all the boats they have for sale (or most of them) and just let people wander through. I found it helpful to just sit on a boat for 30 minutes, without the sales people right there making you feel like you need to get moving. Sit on the seats, are they still comfy after sitting for while? I found a few brands that where just the wrong shape for me, so I scratched them all off my list (unless the inside had been rebuilt.)
And if you find private sellers with boats you are interested in, do not be shy about asking to see it. Sure, you might want to mention you are still in the early stages of looking, and only want to see it if i is not a bother, but many people will be happy to show you the boat anyway. Partly because it is fun and helpful to you and partly because you never know, this might turn out to be your perfect boat, or you might mention it to a friend. Hey, it's part of selling a boat. Do not be too worried about wasting their time, just be honest and go see the ones who have the time for you.
1964 Islander 32
Saint Helens, OR