My school uses Skyward for our SIS and Business Management suite. It's as close to an "all in one" solution that I've ever came across. It uses one database for both "sides" of the solution (student and finance), so there's no duplicate data entry.
As someone else posted, I'd also encourage you to look at Instructure's Canvas product. We're in our second year with Canvas, and have been very happy customers.
Best wishes on your journey!