I would second Sam's suggestion of the North Country Trail. The stretch from Mellen to Solon Springs is complete with good tread and reasonably good signage. Ticks, flies and mosquitos can be bad in May and June, so July, August, and September could be considered "prime" hiking season. But the trail is hikable year round if you plan accordingly.
Sam, you must have been in Montana long enough to forget your Wisconsin geography; your hike was closer to Solon Springs than Mellen ;)