Oh, ya there is Chicago. Can't think of any others off the top of my head.
Though the Chicago river is a lot different than Town Lake. It is only like 150-200 feet wide. It makes me think more of a channel in that part, and the part that does look riverish is more like Barton Springs than Town Lake. Town Lake is more like 600-1000 feet wide, and I'd guess over 800 feet at the part downtown we are talking about.
What I'd like to see is something like London.
The Thames and Colorado are about the same size. And that part of London is probably about 800 feet much like the part in downtown Austin. We just need to build a great big Shard in Austin. Right on the south side of the Barton Springs / Riverside intersection. Bouldin Creek Neighborhood Association would LOVE it! And an Eye next to the Statesman.
Then we could build our own Tube. =) If only......