Rambo,
I hike a lot of small trout streams. I'll usually hike between 3-8 miles. That's why I prefer a hydration fly-fishing pack for access to water immediately. I have the [url=http://www.orvis.com/store/product_choice.asp?pf_id=53XR&feature_id=&dir_id=7 58&group_id=781&cat_id=5093&subcat_id=6670:13505]Orvis Safe Passage Hydration Pack[/url:13505] and love using it. It's a bit pricey though. The [url=http://www.orvis.com/store/product_choice.asp?pf_id=96YT&feature_id=&dir_id=7 58&group_id=781&cat_id=5093&subcat_id=6670:13505]Original Lightweight Safe Passage Pack[/url:13505] is on sale for $69 but you'll have to buy a hydration bladder. The [url=http://www.sierratradingpost.com/p/204,72899_Watermark-Hydro-Vest-Pack.html:13505]Watermark Hydration Pack[/url:13505] is on sale for $44.95 but you'll still have to buy a hydration bladder.

If you do not plan on hiking that much than a mesh vest would be a better idea. Just giving you some more to ponder. Good-luck!