April is never a crap shoot in the Roaring Fork Valley, and normally mid May is a very good bet aswell. I have been fishing the valley for the past 30 years, and my favorite time to fish is September thru Novemeber. The crowds start to thin out, and the Browns start getting aggressive in all three rivers, not to mention the Crystal River.

Drive thru Carbondale and over Mclure Pass, and you will run right into the Gunnison as it exits the Black Canyon (Pleasure Park), near Hotchkiss Colorado.
Head East out of Glenwood and you are 30 minutes from public water on the Eagle River. Keep going in that direction for about 90 minutes and you will be at another Pig producing Tail water, the Blue.
Lots of choices.