if you click and drag on the first row of keyframes, you will select all of the keyframes below.
This is nice because you can either select just some bones, and select all of their keyframes, or, if you press spacebar, you will deselect everything, therefore seeing all the keyframes for all your bones. You can also filter the kind of keyframes (only scale keyframes, or rotation, etc.). Could this solve your problem?(:

Also note you can control what is in the dopesheet. Select nothing, see everything in the dopesheet. Select some bones, see only those bones in the dopesheet (if any of them have keys). Once you get the bones you want in the dopesheet, you can click the Lock Dopesheet button. Once you lock the dopesheet, then you can click the Select Bones button to select all the bones shown in the dopesheet:

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