This proposal is part of our research programme to explore the effects of frustrated interactions and quantum fluctuation on the spin dynamics in quantum magnets. Here we plan to investigate triangular-lattice antiferromagnets with full hexagonal symmetry predicted to display anomalous softening of spin excitations and novel roton-like minima stabilized by quantum frustration effects. We recently synthesized phase-pure powder samples of the S=1/2 weakly-Ising Ba3CoSb2O9 and S=1 Heisenberg Ba3(Ni/Ta)Nb2O9 all with an isotropic triangular lattice with 3-fold symmetry, not probed before with inelastic neutron scattering. The expected bandwidth of magnetic excitations is <3 meV, an energy scale ideal for OSIRIS/IRIS. We propose to search for a small spin gap in the Co material and pronounced signal near expected roton-like soft modes in the excitation spectrum of all 3 samples.