I rode brushy and brown both on a trx450r. Brown mountain is cheap, a few bucks for trail pass. Brushy is close to 30 bucks I believe for a day. Both were challenging on a sport quad. Brushy flows really well, brown was a lot more rough on the rider. I ate shit at both parks. I wouldn't hit brown again on a sport quad, but for a 4x4 atv or 4 stroke bike it would be a lot of fun. Brown seemed a bit choppy to stay in the fun zone for a 2 stroke.
I know brushy has MILES of bike only single track that I never saw. A few short technical hill climbs and the mx track. I was really impressed with their maintenance, and the terrain was used well. I can't remember what loops we took, but we had big plans and a decent pace and only made one full lap.
Edit: realized I avoided answering the question. I would take multiple atvs to brown. Plenty to ride for a day.