Ambari looks nice from the outside but it's some kind of zombie that is full of os-specific stuff, opaque puppet stuff, python, java and even brings nagios and ganglia to the party. If it works it's probably fine, have fun debugging that stuff through.
If you haven't had the chance yet I suggest you try Cloudera Manager & CDH instead of Ambari. I use both with clients and CM is years ahead of Ambari in terms of functionality and stability.
What about for provisioning clusters that don't require Hadoop. I suppose this could be akin to the comment about Redis -- we're working on deploying Kafka, Storm, and Zookeeper (none of which need Hadoop), and provisioning and node management (membership, leader election) in a dynamic environment (e.g. AWS autoscaling) is not at all obvious. There's also a paucity of substantive information about scaling these clusters dynamically.
I'm especially excited about Zeppelin. Using IPython for SciPy and smaller datasets is great. I would love it for the big data space I work in and Python's tooling to come together more.
I recently looked into notebooks and found Beaker (http://beakernotebook.com) to be especially interesting in its support for passing data across languages.
We are happy with https://github.com/saltstack-formulas/hadoop-formula and PXE booting an image.
You can configure all aspects out of a single pillar file.
Still full of warts but at least you have full control.