Best Practices for Web Visualization and OLAP Reporting

I am preparing an offer for a client. They provide weekly data to various organizations. There is a huge amount of data suitable for OLAP that needs to be visualized with charts, and pivot tables in web and custom reports will be generated by non-person (simple gui). They will enter the date range, the location where the columns of the data should be included, and generate a report and optionally export the data to Excel. They are currently preparing MS Excel reports with pivot tables, but now they need the best online tool to show the data to their clients. The tables are huge and need detailing. My current knowledge of Spring, Flex, MySql, Linux. I have some knowledge of PostgreSQL and MSSQL and Windows. What is the easiest way to do this project. Do you think,that SSRP (haven't tried it yet) and ASP.NET are better suited for this kind of work. Actually, I prefer open source solutions. Flex has an OLAP Data Grid control that performs client-side aggregation. JasperServer seems promising, but it seems to me that I need the enterprise version (multiple organizations and ad hoc requests). What about Modrian + Flex + PostgreSQL solution? Any previous experience will be appreciated. Yes, I am confused with options.that I need an enterprise version (multiple organizations and special requests). What about Modrian + Flex + PostgreSQL solution? Any previous experience will be appreciated. Yes, I am confused with options.that I need an enterprise version (multiple organizations and special requests). What about Modrian + Flex + PostgreSQL solution? Any previous experience will be appreciated. Yes, I am confused with options.