The 70-80 stretch in Final Fantasy 14 is tough but the amount of content available also makes things smoother as players have more variety. Thankfully, there are a lot more options now and even DPS can fill in their long queue times with FATES or ignore them completely with Trust Dungeons. However, Heaven-on-High's EXP gain falls off massively at level 70 and it's better to switch content again for the remaining 10 levels.
The same concept applies in that DPS classes will use Heaven-on-High as their main source of leveling, while tanks and healers will typically run the highest level dungeons they can. Once Final Fantasy 14 players reach level 60, they'll have access to Heaven-on-High, which is pretty much the same thing as Palace of the Dead, but in The Ruby Sea.
