Is it still just the odd geographical site/geysers etc or are there genuinely unique things to discover?
In terms of intentional stuff ... there are quite a few types of biological sites (surface and space) which only appear over 1000 LY from the bubble, and sometimes only quite a bit further away than that. Obviously there's only one Sagittarius A* super-massive black hole. There aren't that many nebulae within 1000 LY of the bubble, and some of the best (and biggest) are a lot further out.
There are also things which the procedural generation throws up which can be extremely spectacular ... but extremely rare, and if there were any within 1000 LY they'd have been found by now. My favourite example of this is the World of Death - a landable planet that passes through the jet cone of a white dwarf (sounds like a glitch, but a similar real planet was discovered fairly recently) - so far the only known example is over 20,000 LY from the bubble, though there may be some closer that have yet to be found. Slightly more common than that, but not by a lot, are the Green Gas Giants - gas giants with glowing green patches. Some are greener than others. Someone found a star system with
six planetary bodies in a barycentric cluster - anything over three is rare. There may well be other strange things of that sort that are yet to be found.
Colonia has quite a few unique things ... most people don't consider visiting populated space as exploration as such, but you might as well explore on the way.
And, well, in theory somewhere out there is Raxxla, which is very definitely unique ... but will likely stay undiscovered for a long time yet.