Active Directory Consolidation & Exchange 2010 Migration to O365

Hi,

We are starting some discussions about different options to consolidate Active Directory through different companies. We are all the same company now (after some legal changes) but historically every one has been running their own Active Directory on premise (different location all over the US).  

Currently there are two initiatives happening one is the migration to Office 365 from on Exchange on premise solutions the other one is basically AD consolidation and single sign on from all the different local markets across the US.

I know this is a broad question but I am just trying to get some input about different options to:

1.) Active Directory Consolidation - Maybe Active Directory Azure?
2.) Migration to Office 365

The goal is to be able to get single sign on and a simple way to manage all of the different on premise AD with a single AD account as well as to be able to logon to Office 365 with it.

Anyone?