Have you ever been to Grand Rapids, Michigan? It is Michigan's second-largest city. 
No, but I haven't.  Have you been there?
I go fairly often. Grand Rapids, Michigan is right east of Lake Michigan on the Grand River. It is beautiful.
What are some of the sights or places you would recommend I visit when there?
The river it self it a huge attraction. It is the reason that Grand Rapids, Michigan's nickname is "River City"
I love rivers, so that would certainly be a good reason to visit.  Do you know how big is the population?
Grand Rapids, Michigan
Grand Rapids is the second-largest city in Michigan and the largest city in West Michigan. It is on the Grand River about east of Lake Michigan. As of the 2010 census, the city population was 188,040. In 2010, the Grand Rapids metropolitan area had a population of 1,005,648, and the combined statistical area of Grand Rapids-Muskegon-Holland had a population of 1,321,557. Grand Rapids is the county seat of Kent County.
A historic furniture-manufacturing center, Grand Rapids is
West Michigan
West Michigan and Western Michigan are terms for an arbitrary region in the U.S. state of Michigan's Lower Peninsula. Most narrowly it refers to the Grand Rapids-Muskegon-Holland area, or more broadly to most of the region along the Lake Michigan shoreline of the Lower Peninsula, but there is no official definition for it. 
Definition.
In general, "West Michigan" often refers to the area bounded by the cities of Muskegon (in the north), Grand Rapids (in the northeast)