When you click on an activity in the activities list, there is no "click to go back" button/link. You can click "back" on your browser, or click the activities tab again, but in both of those cases, you are always taken back to "page 1" of your activities. If you've uploaded a ton of activities, and you want to edit 10 of them on page 3, you have a lot of clicking ahead of you. A smart "click to go back" link that takes you back to the page on the activities list that you were previously on would be useful.
This is also a problem with the search activities.
San Francisco is always selected by default.
I was going to mention that one too. Garmin Connect has a lot of usability problems. It is terribly slow, buggy, and lots of simple user interface problems. It took me 13 attempts to upload all the workouts currently in my Forerunner. It would upload a random number of workouts, then stall, I'd start over and upload a few more, stall ...
I'd love to see Garmin Connect replace the Garmin Training Centre altogether (custom workouts, workout calendar etc) but it has a long way to go. Until then I'll keep using the Runner's World training log.