Please add payload information to the ochttp Go integration. This is one of the very helpful items for debugging, and present in the Java implementation and also in the Go gRPC integration. For example, reasoning about why one trace has a higher latency than another, the first thing to look at would be the payload size.

What I found
I tried a modified version of the Go HTTP client tutorial using Zipkin and Stackdriver. They both give similar views omitting the payload size, like this screenshot of Zipkin
with no payload size. It is not nearly as useful as the Java equivalent, which shows the payload size in Stackdriver as events, screenshot:

This could be implemented in the ochttp Go plugin with payload events using code like the gRPC integration in ocgrpc / trace_common.go.