Hiya! I've very little experience playing (let alone GM'ing) a table-top RPG, although I've been an avid reader of fantasy genre all my life (and playing computer RPGs - Baldur's Gate, Icewind Dale, etc).
My only daliance with them came at university but, sadly, the groups there weren't interested in introducing newbies so all I got to do was watch!
Now my kids (8 & 11) are showing some interest in playing these sort of games and I'd like to know if Pathfinder is simple enough for us all to learn together. We played through an RPG named 'Hero Kids' a few times which they really enjoyed but I think they (and my eldest especially) found it a bit simple.
If not Pathfinder, any others for me to look at?
Pathfinder can be complicated, but that can be mitigated. The best way, in my opinion, to avoiding this is to simply not use the full suite of books available to start.
The beginner box is a nice starter adventure to get new players and GMs alike into the game. It introduces the four most iconic classes- fighter, cleric, wizard, rogue- introduces all parties to feats and skills, and gives a few encounters to get into combat.
I'd recommend playing through the beginner's box, and if everyone likes it, grab a core rulebook and keep going from there. In fact, recently Paizo released the core rulebook in soft cover so the financial barrier for entry is lower than it used to be.
The Beginner Box is exactly what you need to try out Pathfinder with your kids.
The player manual should be fine for the 11 year old to read and understand on their own. The 8 year old may need some help.
In fact, if the 11 year old wants, you might go over the Game Master guide with them and see if they'd like to run the simple dungeon there to introduce everyone to the basics of the game.