I would place your mayor house to the southeast of the plaza, so you can have a private little front yard and not have to worry about villagers moving in front of your house. I would wait to place the campsite and cafe until you decide wgere all of your villagers and other pwps are going to be, since they are permanent and can't be undone.
Personally I would go for the Middle, on the north bank, L bend of the river. This is pretty much where mine is and I wouldn't change it for anything. It's real nice if you build a bridge straight from your house over the river too. Just leave yourself enough room for custom tiles or plants, and how you want them round the house.
In my alt town I placed my house right beside the entrance to town, thinking that would be good...it's terrible, lol.