Need some ideas

Ok, hm...

Let's start with some ideas on Arborea - there's Pelion where you can touch on the Words of Creation. I don't suggest doing that till the end of your campaign. There's also the Greek deities of Olympus, given your interest in touching on the Blood War - you can get to Carceri (and the Blood War) from the Olympians via the imprisoned titans. Carceri is the plane of imprisonment, so I'm sure you're already familiar from Ravenloft of things you can do to a player in a giant prison environment.

Ysgard - obvious, "go fight stuff". Not so obvious: you could have him become involved with the drow on the third layer there - they're good(ish), and isolated - so vulnerable to being attacked by the ignorant who are used to the evil-drow. Similar scenarios exist with the ratatosk, as they are basically giant intelligent squirrels. Threats to the Great Tree could get you from Ysgard to the Blood War, since the Tree's roots are in the Waste which is where the Blood War's yugoloths center.

For the Outlands, Blood War armies and mercenaries routinely use sections of the Outlands to travel upon. There's also plenty of slavers and other nefarious icky people to beat up. You could also pick up on the theme of the Free League vs. Estavan's Planar Trade Consortium (the small business man vs. the corporation). There's also the Hinterlands of the Outlands to play with his head some - that's where you're likely to find thigns that just don't 'fit' elsewhere... and where you can bring up some Ravenloft style if you want to go dark truly dark.

Let me know if you want more details on any of these ideas, I don't want to squish your prerogative as DM by going too detailed too fast with the ideas.