A complete variational treatment is provided for a family of spiked-harmonic oscillator Hamiltonians H=−d2/dx2+Bx2+λ/xα(B>0,λ>0), for arbitrary α>0. A compact topological proof is presented that the set S={ψn} of known exact solutions for α=2 constitutes an orthonormal basis of the Hilbert space L2(0,∞). Closed-form expressions are derived for the matrix elements of H with respect to S. These analytical results, and the inclusion of a further free parameter, facilitate optimized variational estimation of the eigenvalues of H to high accuracy.