I am looking to hear from others around Salesforce adoption/utilization, custom development, success measurements, and better understanding "value realization".  We are managing a global "core" platform of Salesforce (Sales and Service Clouds) across multiple regions globally. Does someone have experience, challenge and success stories?

We had a very similar experience to Jessica, we have done 2 global implementations. The first instance was too customized and it was hard to manage across the regions and it was preventing us to use some of the new out of the box features. Salesforce functionality and product are also more reach and wide than 10 years ago when we did the first implementation, which meant that in our second implementation we used mainly out of the box solutions and any customization was going to a review board (with IT and business) for approval. The important thing if you want to avoid customization is to align and streamline the processes before implementing and have very clear guidelines / principles to drive decision making.   

We're on our second deployment of SalesForce. The first was very customized, and did not scale with the business. The second has a governance process that limits in customizations that could break with SF.com enhancements. This process does allow us to tailor SF.com for businesses via a council. Any business can bring forward customization needs, which gets evaluated by the central IT function (how "custom" is it really? will it break with SF.com enhancements?) and then rated with a low, medium or high effort, which dictates when / how it might get deployed. The requirements are put out for consideration / amendment by the other businesses in case the function might also be useful to them. Once implemented, the function is simply opted in or opted out by each business. This keeps our businesses aware of full function available, as well as central guidance that allows base SF.com enhancements to roll out over time, while still tailoring the tool to meet business needs.