I've just been shopping for flights next summer to Europe and discovered that I couldn't seem to find availability in Economy Plus seating even though I do have an annual membership. When I called customer service (???) I was told that I actually had to purchase a ticket now before I could book my Economy Plus seating. When did this go into effect? What if I don't like the seating after I've purchased the flight? Does anyone know if this is true and when did it change?

You are very early for buying a seat for next summer. The E+ section is wide open for your flights.

If you don't like the seating then cancel the ticket within 24 hours and get a full refund.

No one in my family has the annual E+ membership, so I can't say for sure, but that sounds a little strange to me. The website says "You'll be able to confirm available Economy Plus seats for yourself and a traveling companion <b>at the time you make your reservations</b> - for an entire year." Does your subscription end before the period of travel that you're searching (although I thought I read that the subscriptions auto-renew)? Are you sure you were logged in when searching?

I'd suggest calling again, or writing. I found this E+ specific customer service address on the website:
EPACustomerService at united.com

Otherwise, I agree with mrwunrfl; E+ will be wide open for flights next summer. It is still wide open for most of my flights this fall.

Never had that happen to me--as long as I go into the UA site logged in I can see the UA e+ seats.

What dates and cities?