the biggest challenge is making sure the spreadsheets are in a standard form
typically you would create an SSIS package to import all of the spreadsheets into the DB first
I'd dump them into a RAW type table w/o any strict data type definitions
Then I would I inspect the data imported and flag any imports that did not conform to the standard (the better your test here the cleaner the import will go). I don't know how many spreadsheets you are talking about here, but the more data you need to import the more important this step is. Also I don't know if you have multiple tabs in each file or what.
Once you have acceptable data in the raw tables you can start normalizing the data into a better relational structure. You can work on the ERD of your table layouts first to better organize their Assets.
I believe you can use the SSMS GUI in order to import 1 file, and then save it as an SSIS package if this is new to you and then edit the SSIS package in the BI designer application.