MedBow/Snowy Range is where most of us go when we don't draw our limited-quota tag for the year. Access is generally pretty easy, which translates to "don't be surprised if you run into other hunters".
Weather during archery is generally pretty good, it's the rifle hunters that get snowed in. Nonetheless, if you're hunting in later September, you need to be prepared. Weather will affect the elk, too - you might be in the middle of hundreds of them one day and find yourself alone the next with a storm blowing in. As well, the pine beetle has wreaked havoc on the forest, be careful selecting your campsite and parking your truck. Lots of trees tipping over now there were killed over the past couple of years. I never go up there anymore without a chainsaw.
It's beautiful country, but there's a lot of it to cover. I haven't hunted up there for the past seven years, so I'm not a very good resource in terms of the best places to start. I've never hunted the Sierra Madres, but I know quite a few people who do and prefer it over the Snowy Range. I think access may be more difficult and less hunting pressure as a result.
Definitely worth a scouting trip.