If you're gonna run the Dolores, go NOW 'cause flows won't last. If you're headed for the San Juan, you must have a permit and right now the river looks booked (just looking at the river calendar). If you entered the permit lottery on the SJ, you are eligible for cancellations. If you didn't enter, you can't get a permit this year.
SJ River calendar linky...
http://www.blm.gov/utah/monticello/river.htm
On the other hand, the lower SJ presents almost nothing in the way of whitewater and is a spectacularly scenic float. The biggest rapid is Government, and it's an easy 3. Easy portage, too.