It's hard to beat Mexico for waterfalls runs.Micos is perfect set up for what you want to do;boats available,drivable from US,big but easy/low consequence drops,stuff to move up to [Minas Viejas-El salto ] and other good runs in the area.
Alsaseca in Veracruz is maybe 4+[ harder sections nearby] and has lots of sliding falls and some verts,and there is a whitewater industry so boats/boaters.
Agua Azul is Micos on steroids,the largest travertine formation on earth= over 500 waterfalls from III to soil yourself.Plenty of boaters have been there but you're on your own.Chiapas is full of waterfalls of all difficulties,AA is the highest concentration and easy access.
Las Conchas is the Micos of Guatemala mostly 8 ft . and under III'S and a 30 ft. V,other runs in Chiapas ,Guat.,Belize,a 1/2 day away b y o boat. You can fly to Guat. as cheap as Mexico and have a hard time spending $50 a day.
Moho River in Belize ,60 drops 3 to 18 ft. travertine ledges,forgiving III+.
If you happen to be on the Croatian/Bosnia-Hercogovinia border check out Plitvice Natl. Park,in Vallhala or Wehyakin',the Agua Azul of Europe.
One route from Cali to Idaho,could take you around the Yuba /Pauley/Lazzevola creeks then across Nevada into NW Utah for Sixth Water,Big Cottonwood,and the Provo,all waterfall and/or big slide runs.