The Fox River State Recreational Trail stretches about 25 miles from the City Deck in Green Bay to Greenleaf. I have so far only explored the Green Bay and DePere portions of this trail.
This trail is wide enough for two strollers side by side going either direction once you get about a mile from the City Deck. The City Deck area has a brick pathway that is wide enough for one stroller and another person next to the stroller but a little tight for two.
After Voyager Park in DePere the trail does get slightly narrower but still ample room for two strollers side by side. It is kept up very well. No potholes to twist an ankle in (that's a different trail). Following this trail there is also a Fitness Mile that has stations for certain exercises. I plan to head back to do that very soon and make it part of my weekly routine. The past few times I've ran this route, I've skipped the fitness mile and focused more on my running time. At some point the trail switches to crushed stone rather than asphalt but I have yet to explore that area.
This run I did Monday and ran it alone! It was very nice to not have to push the jogging stroller but there was also no where to put a bottle of water :(. There are, thankfully, two spots along the way with water. One is near the fitness mile about two miles past the start point and another is the boat launch about a mile before Voyager Park.
This, by far, is the most stroller friendly trail I have come across and this is where I typically do my runs that are longer than 4 miles. Extra above and beyond bonus, this trail has markers every tenth of a mile from the 1.2 mile mark to Voyager Park (and possibly beyond the park, but as I said, haven't gotten that far yet :) ).
The landscaping of the houses along this path is also quite amazing. Another house along the way the garage lines up with the path and often the older gentleman who lives there is out in his garage with his band practicing. Gives a nice lift to my run for a little bit anyway. This trail is also dog friendly so MudPuppy gets to join me often on this one :). Some of the others are too narrow to really do well with him and the stroller when passing others.