I’ve been checking the major airlines for routes and prices for a month now.
I’m going to be flying into Prague June 13 from PHX and out of Vienna July 4.
United has a mixed cabin option giving you premium cabin on the long flights through Austrian Air with a price of $1372. Doesn’t look like you can select your seats on the Austrian Air legs. Does anyone have experience with United and this class of travel, will I be able to select my seats?
I have not flown Austrian Air but have heard some good things about them. Go to seatguru.com and check out the seat dimensions and reviews. Be sure you plug in the exact details for your airline (the one whose plane you're actually on, never mind who sold you the ticket), your specific travel date, your specific flight number. Seatguru is not perfect (the occasionally get an aircraft type wrong, some info may be out of date) but it's a very useful starting point to give you insights into what the butt-in-the-seat experience will be.
I wouldn't assume that you can't select your seats, unless United and Austria tells you that specifically (call and ask them). You probably just need the Austria Air record locator number for that segment (you can NOT use the United confirmation number on another airline). You can find that (Austria Air record locator number) when you log in to your United account and pull up your reservation (if you can't find it online, call United and ask them to give you the Austria Air record locator number, write it down and save it, it's critical info!). Then you can usually go to the operating airline's website (Austria Air in this case) and log in THERE to "manage my trip" or something similar - then you should be able to select seats. This is typically how it works for almost all partner airlines. Just be sure you get that Austria Air record locator number.
Good luck and have fun.