Straight answer: not on a two-day city break. On a longer stay, or if you are in Grand Rapids for work and want an hour outdoors that is not a pavement, yes.
Choose Provin Trails if you want quiet, natural-surface trail close to the city, a short trail run, or snow underfoot in winter without driving to a resort.
Choose Blandford Nature Center instead if you want interpretation, a staffed visitor centre, wildlife enclosures and something suitable for small children. It is on the other side of town and does a different job.
Choose Millennium Park instead if you want paved paths, water, and space for a family with bikes. It is much larger and far more developed.
Choose Riverside Park instead if you want to walk beside the Grand River with a paved surface and a disc golf course attached.
The sequence that works well for an autumn Saturday: Provin Trails for an hour, then the orchard immediately north for cider and doughnuts, then back into the city by mid-afternoon. That is a genuinely local day rather than a visitor itinerary, which is the point of it.