Once it's running yes. But if you close Spotify, pressing the play key will start iTunes. It's quite infuriating.

Also try clicking a mailto link. I'm sure that about once a day I see the dialog asking me to add an account into the default mail app.

Basic integrations between MS Office apps also seem to be missing, I'll be damned if I can find the menu to send a copy of the document I'm working on in Word to a contact in outlook.

Mailto links open chrome with a gmail tab for me.

I just successfully changed it, but it was a janky experience. Until I added an account to the mail app, the preference used to change the default email reader remained greyed out because I was being prompted to add an email account. Only once I added a fake account did the preference option become available and let me change the default mailto handler. Removing the fake email account caused the preference to become greyed out (but it retained Outlook as the default).

Here's another example: Try and change the right click -> search with google menu option to 1) not open in Safari and 2) search using another search engine.

I did it this way by accident : I installed chrome and logged into gmail. Chrome asked me if I wanted to make gmail the default mail app and I said yes.

I would have NEVER discovered that this would be even possible any other way. I don't know if it works on other browsers but it's cool that it works.

On right click in chrome I have two "search with DuckDuckGo" options and one searches on a new tab and another on the same tab. I don't know why.

This kind of thing has actually improved over time, though. It used to be (back in 10.6, at least) that the play/pause buttons always affected iTunes, even if you had, say, VLC running. It would just also affect VLC.

Have you tried Bowtie or BeardedSpice?

http://www.makeuseof.com/tag/mac-users-heres-control-streami...

I use Bowtie for a few things, but haven't really tried it for this purpose as I pretty much just use iTunes as I have several decades worth of music I've bought in it.

http://bowtieapp.com