Fall River is fishing quite good, look for hatches of PMD, Caddis, Midges, BWO and Green Drakes now. Ants are a favorite of mine out there too. Beetles are great.
Fishing is good all over the river so spread out and find some space. It gets busy from 10 or 11 AM to 3 or 4 PM pretty much every day. Try going at dawn, or go for the evening to mitigate that a bit.
Nymph opportunities are endless when you find the fish. A single nymph (usually mayfly or midge with tungsten beads) on 6 1/2X or 7X is going to do the trick. I often opt for the single nymphs there over the dropper rig for 2 reasons: in flows like the Fall, one nymphs penetrates best and without a 2nd nymph there is no micro drag on the 1st nymph. #2, so often we end up fishing in the logs or close to them anyway, and one nymph fishes more accurately than 2. Plus, when you lose the fly in the log, it is certainly less painful when it’s just one at a time.
When we had Tom Jarman here from the Australian Fly Fishing Team in 2018, he is a master of flow and he taught me, and showed me the difference a single nymph can make in getting a perfect drift in linear flows like what we see often in rivers like the Fall. Think about the lava ledges and how that created micro eddies and currents that can suck one fly a different direction. Of course some of that can be countered with heavier beads, or swinging Euro Streamers. But for pin point casting to specific trout, try the single nymph.