You can spectate challenger players now!

The feature may have been around for a few patches, but I found it now and I'd like to share.

First, you have to go into your profile, and go to ranked section. This will show you your ranking. Near the top right, select the drop down menu that says "Solo/Duo" or "Flex 5v5." Now change that to anything in Challenger Tier. You can spectate Solo/Duo, Flex 5v5, or Flex 3v3 of top ranking players.

This doesn't let you see which champions were picked or banned until you load into the game, but you will still be able to spectate high elo gameplay.