I'm looking for manga that involve a lot of politics in a royal/ruling family. Like about arranged marrages, successors, power struggles, etc.

It can be any kind of manga except Hentai. It doesn't have to have romance but its fine if it does..

Feed your head.

Princess
Rose of Versailles

[url=http:////www.mangaupdates.com/showtopic.php?tid=42718][img]http://i366.photobucket.com/albums/oo105/CatzCradle64/Avis-Sigs/FunghiPower_zps2a00ba56copy_zpsfc03990e.png[/img][/url]

Adarushan no Hanayome
Zettai Heiwa Daisakusen

Goong

Tumblr

Basara
Cesare
Historie
Kago no Naka
Ni no Hime no Monogatari
Saiunkoku Monogatari <-- start with the anime of this one 🙂
Red River
The Scarlet Chair
Vinland Saga

Avatar by tassyn.livejournal.com

Reading: Kingdom, Sangokushi, Historie

Quote from CatzCradle

Princess
Rose of Versailles

Beat me to them.

Also:
Cantarella-Light shounen-ai. But the historical content and political family fit your description exactly.

(The author, Higuri Yuu, writes a lot of historical fiction.)

Note that all three of these are shoujo titles.

I second the Saiunkoku Monogatari anime.

Dawn of the Arcana - first scan just came out today. It looks interesting.
Hiiro no Isu
Goong
Real Fake Princess
Red River - very long epic saga. Honestly, I got a little bored with it and stopped reading at vol 21, but it has plenty of power struggles, succession issues, and politics to it.
Akagami no Shirayukihime
Kaze Hikaru - not with a ruling family, but deals a lot with the political turmoil and power struggles in mid-to-late 19th century Japan.