Brown's doesn't have any IV's (except maybe Seidel's at certain levels) and neither does Stone Bridge to Rincon. Brown's is mostly III with a couple III+'s but gets technical under 500. SB to Rincon is III- with a couple III's.
Brown's would be a step up from SB to Rinc but would might be doable for you guys with a guide. If it's running, you might want to look at the Lower Blue. Also, the Colorado from Shoshone down to Two Rivers Park or South Canyon would be good (put-in above Shoshone if you're feeling good or below if you want mellower). This will definitely be running. You could also do the Upper Colorado from Pumphouse to Rancho, Statebridge, Bond, or any other take-out (this has decent camping, a hotsprings, cliff-jumping, and some solid III's in mostly II-III scenic setting).
"The world would be a better place if everyone kayaked."-Brad Ludden (Valhalla)
"You only get one chance to run a drop blind."-DD