One of the more challenging parts of writing anything in the far future is what I call mundane tech. The everyday things that you use without thinking about. Things like washing machines, books, or desklamps.
It may not come up often but you do need to consider how those things will look in your book. If I am reading a book set in the year 3,834 I expect EVERYTHING to be better, not just the big ticket items like power generation.
Once you have a grasp on the big leaps in technology you should just sit back in your chair and look around. Look at everything in your room and ask what you would be using instead if you lived in the world of your book.
This also will let you know if you really do have a good grasp on the basics of your world’s technology. You SHOULD be able to do this, if you can’t then you may need to think about going over your technology again.