The Coerthas Central Highlands are a great place to grind fates at the above mentioned levels.In fact most days you can join a party to just by being in Dragon Head and watching the shouts. Though past 42 the higher level fate's are far and in between.

Svara;s Fear/Fury/Fall is the major xp in the area, 15 minutes for 40k.

Exact details on these fates are here.
http://xivdb.com/?search/!filters/IkZBVEVTOkZTRl9QTjE1NTpGT0ZfRk9GTFZMX0ZPRkFTQzoi

Twelve Ilms Of Snow
Lv35 Coerthas C.Highlands

Gavial
Lv35 Coerthas C.Highlands

A Log Up
Lv35 Coerthas C.Highlands

Whiteout
Lv36 Coerthas C.Highlands

Coldblooded
Lv36 Coerthas C.Highlands

Wish Upon A Star
Lv36 Coerthas C.Highlands

Baa Baa Black Sheep
Lv36 Coerthas C.Highlands

A Fire In The Distance
Lv37 Coerthas C.Highlands

Coming To A Head
Lv37 Coerthas C.Highlands

Svara's Fear
Lv38 Coerthas C.Highlands

Simply Red
Lv38 Coerthas C.Highlands

Svara's Fury
Lv38 Coerthas C.Highlands

Svara's Flight
Lv38 Coerthas C.Highlands

The Grey
Lv38 Coerthas C.Highlands

Svara's Fall
Lv38 Coerthas C.Highlands

Spring Forward, Fall Ba…
Lv38 Coerthas C.Highlands

A Freeze Is Coming
Lv39 Coerthas C.Highlands

The Eyes Have It
Lv39 Coerthas C.Highlands

Roc Of Ages
Lv39 Coerthas C.Highlands

Bellyfull
Lv39 Coerthas C.Highlands

Judge, Jury, And Execut…
Lv39 Coerthas C.Highlands

Riddle Me This
Lv40 Coerthas C.Highlands

If This Wall Could Talk
Lv40 Coerthas C.Highlands

Giant Seps
Lv40 Coerthas C.Highlands

The Taste Of Fear
Lv40 Coerthas C.Highlands

Front And Center
Lv40 Coerthas C.Highlands

In The Saint's Wake
Lv45 Coerthas C.Highlands

Tower Of Power
Lv45 Coerthas C.Highlands

The Bigger They Are
Lv46 Coerthas C.Highlands

What's On Your Mind
Lv47 Coerthas C.Highlands

Turn Off Your Hearthlig…
Lv47 Coerthas C.Highlands

Does Anyone Hear It
Lv48 Coerthas C.Highlands

Inspector Hatchet
Lv49 Coerthas C.Highlands

The Four Winds
Lv49 Coerthas C.Highlands

He Taketh It With His E…
Lv50 Coerthas C.Highlands

Behold Now Behemoth
Lv50 Coerthas C.Highlands