Looking at upgrading using miles on a trip to Europe next year. Is there any way to do that on the front end or do you have to book your ticket and then either call to upgrade or do it somehow online?

Hope that made sense.

You have to do it on the phone, you could probably hold your trip online and then call to pay for the trip and request an upgrade at the same time if it matters, otherwise just book the flights and then call to make the request.

You will probably be put on a wait list depending on your status and the demand. If you have status you may look out for the $ upgrade offers AA will send you after you book, to the detriment of EPs hoping for a free upgrade they are have been giving away $ upgrades for a song the past year (be patient) but I think that you have to have status to qualify for the offers (may be wrong).

If you search on expert flyer you can see if flights have available upgrade seats. If there are any upgrade fare inventory, you can upgrade when you purchase the ticket. You will not find a lot of upgrade inventory on AA but you may get lucky. You can always get on the list for a miles upgrade.