My mistake, it was 164 km or so. Rather have that than any other estimates. We can technically follow that as the highest canonical source, even beyond movie visuals or "what sounds cool" to paraphrase Leland Chee. These people actually made the things. No one should have more say over the designs than their creators. As for the hologram in ROTJ, I wouldn't put much stock in that, given holograms are meant to be tactical. The one in TPM showed the secret corridors in the palace as being pretty huge compared to the actual building, iirc. For ease of viewing rather than accurate scaling. Same with the barely zigzagging corridor view on the DSII hologram vs. how the interior actually looked like when they were flying through it.