I attended USO on Monday and Wednesday.
For Monday we pre-booked Grandstand tickets, lucking into $85 standard tickets in the 2nd row. Now that we attended I will say that we voluntarily moved back several rows for a better view. the first rows are sunk to a lower level than the court so it provides very weird viewpoint. I would suggest that 6-10 rows up would be ideal, if you go the pre-booking route. We only ended up watching one match in GS and simply chose any other matches we wanted to see on any other non-Ashe court.
For Wednesday we purchased a grounds pass.
Please note that we showed up at around 11:00 am on Wednesday and, after going through the entire ticket line and the security check, we got to the ticket counter and they told us they had no tickets other than the $390 courtside Ashe tickets. We were devastated after traveling all the way out there and going through the lengthy line. We wondered why they didn't they tell everyone at the start of the line that only the super expensive Ashe tickets were left. We moaned. We pleaded. "Aren't there ANY other tickets left? How could you be sold out so early in the day, so early in the tournament? It was to no avail. We hovered. We slowly waddled down the long ticket counter line, not quite ready to admit defeat. As we stood at the end of the long ticket counter we overheard another couple asking the last ticket counter agent about the lack of tickets. He said that there were no tickets but that there was a chance that more 'general grounds' passes would be released. Lo and behold, about 2 minutes later, the counter agent mentioned that there were grounds passes available. So, we snagged a couple.
One general comment on the temporary Armstrong stadium...it kind of sucks. Due to the set up it really only has one access point. This creates a line up, even when the stands aren't full. Then on change overs they let a batch of people in, but the people don't have time to make it around to the other side of the stadium, so there is always lots of jockeying and moving about during the match as people try to get to other areas during the the switch overs. The movement inevitably spills over as the players begin to play.
In the end I vouch for the incredible value offered by the grounds passes in the first week of the tourney.
ETA: I should add that by going in the first few days you get a huge selection of singles matches to chose from. We saw, Zverev v Coric; Kyrgios, Sock, Johnson, Shapovalov, Rublev, Bedene, Muller, Lorenzi and others. We could have easily watched Thiem, Fritz, etc. but simply didn't have the time and had to chose.
