I had remarkably good success finding tickets yesterday from ZRH-SAN in late July. The awards I found went via DUS, connecting to DUS-ORD and then to SAN. This was for saver biz at 50K one way. I had to book sequential days for my husband and me; I couldn't find space on the same flight. Also undesirable was that I could only find the schedule with a forced overnight in DUS. Today, I checked again and found space for 2 on LHR-DFW, one in F, one in C. We are on the same planes from ZRH-LHR-DFW-SAN. For this ticket combo, it was essential to accept an overnight in DFW before our onward flight to SAN. I put these tickets on hold and canceled the tickets via DUS. Fees for tickets via DUS were roughly $75 each. Fees via LHR are roughly $175 each.

I usually find much better availability with Star using my UA miles. This time, when I checked, I found nothing in any cabin for a month around the date I want to fly.

I say all this to encourage you. Availability shifted between yesterday and today. If I were you, I'd check twice a day. You can also set up a daily search using awardnexus and specific flights using Expert Flyer. I believe that AA continues to allow changes with no fee if you keep the originating and the destination cities the same. You can change routing with no penalty. I'm hoping to improve my own awards but at least I do have something I can fly if need be. It does seem, though, that your quest for a coach seat will be more challenging than mine for Biz or F.