rewarding exploration

I have been playing in survival recently on a server with friends, one of the things that sounds really fun to us is the idea of going out and finding all sorts of cool generated villages, mineshafts and so on. Exploring them is really fun, but it feels like as we find things we find that there is little reward system for our search. For instance, mineshafts have random chests that you can look for for loot, and when you first search it's pretty fun because they give you seeds that you likely don't have yet, but once you search one or two you pretty much have everything they have to offer, seeds, saddles etc. I would like to see more unique items as rare drops, if music discs had small chances to drop in these locations then you would have a goal to search unique locations like this and you would feel like there is a long term reason to search for unique locations, and it would be nice if minecraft expanded on the set of unique items that you can collect, like paintings exclusive to loot, or other cool ideas people can think of.