Without doing too much searching I suspect that you are correct and that they are all closed. San Diego is an easy place for an outdoor vacation though. Balboa Park, even with the museums being closed, has beautiful architecture and a lot of hiking trails, the San Diego beaches are opening (Tuesday 6/2), and Coronado is an easy drive from the Gaslamp quarter. The downtown area is great for walking and it's really not that far to the embarcadero and a beautiful walk along the waterfront. And if you are a golfer, there are a lot of courses to choose from. So, still a lot to do. (Btw, I have nothing to do with this listing or resort, just wanted to offer some additional vacation planning options if the traditional downtown venues are closed).